What can you charge for when the ideas are already in your book?

You can charge for additional help applying those ideas: working through a reader's situation, preparing a useful document, checking work against your method, or providing clearly bounded personal feedback. The reader should be able to see what the second purchase adds before buying it.

Start with that additional job. An AI version of your book is a format description; it does not yet explain why someone who owns the book should pay again.

For an established nonfiction author, this is also a question of trust. Your readers bought a book that promised to help them. A companion offer should make that promise easier to act on without suggesting you withheld the useful part.

Here is a practical way to draw the boundary, including a worked example you can adapt to your own method.

Some readers understand your explanation, apply it themselves, and need nothing else. That is a successful outcome for your book.

In a discussion of Donald Miller's books, Reddit user u/othersongs wrote:

“I have no desire to get anything further from Don, but his books are totally worth it.”

The commenter described enjoying the books and using their concepts. They were not reviewing the paid training or complaining about its quality. Their account is a useful reminder that a satisfied reader can reasonably decline the next offer. Read the original comment.

Design for the reader who has a further task, rather than treating every book buyer as an unfinished sale. That reader might know your method yet struggle to apply it to a messy project. They might need a repeated check, a structured first draft, or feedback on a difficult choice.

Ask: What has this reader already learned, and what do they still need to do?

If the answer is simply “remember the main points,” a summary may be a useful reader bonus. If the answer is “turn this incomplete project brief into a usable plan,” you have a more specific paid-offer hypothesis.

These are three different promises.

Explanation helps the reader understand the method. Your book may already do this thoroughly. Reorganizing its chapters into a chat interface can be convenient, but convenience needs to be demonstrated rather than assumed.

Application helps the reader use the method on a particular task. It might ask for missing context, identify a contradiction, or help create an editable output. The useful difference is visible in the work the reader leaves with.

Personal attention means someone actually spends time on the reader's case. It could include your review, a mentor session, or a facilitated discussion. State who provides it and what is included.

In a historical discussion of Building a Second Brain, u/michelle1908 described taking the course and wrote:

“There were also optional small group sessions with mentors when I took it.”

The commenter explicitly cautioned that they did not know whether future programs would include those sessions. This is an account of human support in a past course, not a statement about the current offer or evidence that an AI companion provides equivalent help. Read the original comment.

Keep that distinction in your own description. A skill that applies instructions is not a private session with you. If your proposed product includes both, describe each component separately.

Consider a fictional author, Nora, whose book teaches practitioners to design useful workshops. Everything in this example is invented for illustration. It is an offer-design exercise, not a report of a working product or customer result.

Her book explains how to define a learning purpose, choose a practice exercise, prepare materials, and work within the available time. Her free companion is a complete one-page worksheet. Readers can use it without buying another product.

The proposed paid skill would help a reader fill out that worksheet for an actual workshop, using Nora's instructions. Here is the boundary:

Notice that Nora does not remove the worksheet's instructions to make the paid option necessary. The reader can still do the work independently. The proposed product must earn its place by making the application help useful.

Before: a broad workshop request

The reader brings this fictional note:

Run a one-hour workshop on giving useful feedback for twelve new team leads. I want them to practice, but I have not chosen an exercise or prepared examples. The session is remote.

A summary of the book could explain why workshops need practice. Nora's proposed skill needs to go further with this particular note.

For example, it should ask what kind of feedback participants need to give, what prior experience they have, and which remote collaboration tools are available. Those answers have not been supplied. Inventing them would make the brief look finished while leaving the actual workshop poorly prepared.

After: a draft with visible gaps

An illustrative target output could be:

Purpose to confirm: Participants practice writing a specific, actionable piece of feedback. Confirm whether written feedback fits their actual work.

Audience: Twelve new team leads. Prior experience and accessibility needs have not yet been supplied.

Practice proposal: Revise an intentionally vague feedback example, then compare revisions against the criteria taught in the session. The facilitator must choose suitable criteria and examples.

Materials needed: A fictional feedback example, revision criteria, and a way for participants to share their drafts. None has been confirmed yet.

Constraints: One hour, remote delivery. Confirm tool access before proposing breakout rooms or shared documents.

Next preparation step: Confirm the objective and tools, prepare the example, then allocate time for instruction, practice and discussion.

This is a hand-written demonstration of the intended deliverable, not an actual AI run. A real product would need testing before Nora could promise it produces comparable work.

The additional utility is specific: the broad request becomes a usable preparation brief with omissions exposed. The reader still confirms the objective, prepares appropriate materials, and facilitates the session.

Take one recurring question from your own readers and complete these six lines:

1. The book already helps the reader understand: Name the principle or procedure.
2. The reader is now trying to do: Describe one task in their own work.
3. The proposed companion will help produce: Name a document, plan, review, or other inspectable output.
4. It needs these inputs: List what the reader must bring.
5. The reader remains responsible for: State the decisions and checks you cannot take over.
6. My personal involvement includes: Specify actual support, or state that personal review is not included.

For Nora, those answers might be: workshop design; a feedback practice session; an editable workshop brief; the purpose, audience, possible exercises, materials, and constraints; verifying suitability and running the session; setup support with no personal facilitation.

Now remove the words “AI,” “exclusive,” and “premium” from the description. Can a reader still explain the additional service? If the offer becomes hard to describe, work on its scope before choosing a name or price.

Our guide to writing an agent skill can help turn that scoped task into instructions. The commercial question comes first: which part of the reader's work are you offering to help with?

A companion resource does not have to be sold separately. You might include a checklist, examples, or a simple worksheet with the book because that fulfills the book's promise well.

James Clear's official reader page, for example, offers purchase-confirmation bonuses including a habit tracker and companion reading guide. The page also describes a free email course. These are examples of useful companion material without an additional purchase on that page. Atomic Habits reader resources

Use your own reader relationship to decide where that boundary belongs. If you advertised a downloadable worksheet with the book, honor that promise. If readers need a correction to understand an example, do not turn the correction into a new premium feature.

For optional additional help, show a representative sample. Give readers enough information to choose among doing the task themselves, using the free resource, and buying the companion. A clear reason to decline helps define whom the paid offer is for.

For the fictional example, a weak description would be:

Get my expertise on demand and transform every workshop.

It leaves the output, limitations, and author's involvement unclear. A more concrete proposed description would be:

Prepare an editable workshop brief using the method in my book. Bring your purpose, audience, available materials, and constraints. The companion helps you consider a practice exercise and organizes your confirmed answers. You review the brief and run the session. Personal workshop facilitation is not included.

That language still needs a demonstrated product behind it. Do not publish the description as an available offer until you can deliver its stated behavior.

If maintenance is included, name what it means: corrected examples, revised instructions, or support for a stated period. Avoid an undefined promise of lifetime improvements. If personal review is included, specify what gets reviewed, by whom, how often, and within what response window.

Keep the billing decision separate from the value description. A recurring charge needs a recurring reason to buy and a clear account of ongoing obligations. A reader preparing one workshop may need a finite product even if another reader uses your method every week.

Before selling broadly, show a few suitable readers the book's existing resource and the proposed companion on a task they recognize. Ask them to point to the useful difference.

For Nora, that means asking whether the preparation brief exposes something the reader would otherwise have missed, whether its questions fit the situation, and whether the reader can use the draft without extensive cleanup.

Record objections as specifically as praise. “I already do this with the worksheet” is useful information. So is “I would need your personal review before trusting this.” The first may identify a reader who does not need the product; the second may reveal that the proposed automated help is insufficient for that task.

This small exercise does not prove market demand or dependable performance. It helps you revise the promise before asking more readers to rely on it. Use a proper skill test to examine behavior and failure cases separately.

You do not need new ideas merely to justify a second purchase. You need additional work worth helping with, a visible deliverable, and a promise you can keep.

If you have that task in mind, visit Skillfully and choose Book onboarding. Bring one reader question, your existing book resource, and a sample of the additional help you want to offer.