Can I move a project to another computer?

Yes. Because books live in the browser, you move one deliberately:

1. On the first computer, open My Books and click the ⬇ (download project file) button on the book. You get a single .json file that contains the whole project — including your manuscript and settings.
2. Move that file to the other computer (email it to yourself, a USB drive, cloud drive — whatever).
3. On the second computer, go to My Books → Open project file… and select it. The book opens, ready to keep working.

Your purchases move separately. Sign in on the second computer and your license keys sync automatically, so anything you've unlocked stays unlocked — no need to buy again.

Without carrying a file

If you're signed in on both machines, the ☁ button on the book card backs the whole project up to your account, and you can open it on the other computer straight from My Books. Same content, no USB stick. See How do I back up my project?