Where can I find projects I've already purchased?

For iOS:

You may find all of your previously purchased projects on the Projects screen by toggling over to the Purchased tab. Projects that have not yet been purchased will be listed under Drafts. Archived projects will be listed under Archived.

For Android:

Tap the main menu (3 black lines in top left corner) and then tap My Photo Books. All drafts and purchases will be listed here.