We want you to be able to poke around and build the whole shape of your book before anything costs a thing. Here is exactly where the line sits.
Free: browsing and building
Signing in, making a World, adding characters, writing settings and props, starting a book, and typing every page of your story are all free. You can lay out the entire book, cover to cover, without spending anything.
Uses credits: making illustrations
Turning your words into a picture is the part that uses credits, and that needs an active subscription. Each illustration you generate draws from your credit balance. This covers page art, cover art, and the reference pictures you generate for your cast, settings, and props.
Two things protect you here. First, if a page needs a character who has no reference picture yet, the illustration is refused before you are charged, so you never pay for a picture that could not know who to draw. Second, a two-page spread (one wide picture across two facing pages) is a single generation and a single charge, not two. More on that in two-page spreads.
Free: exporting your finished book
When your book is done and you want the files (a print-ready PDF, an ebook, a cover, or plain page images), exporting is free. You already paid to make the art, so taking it with you costs nothing. You can re-download your exports whenever you like. See export formats.
If an illustration ever gets refused, the short reasons are gathered in why an illustration was refused.