You can easily save your photo book online in your account. Just click on the "floppy disk icon" at the top left of the product designer. After a moment, you'll see a message saying "<1 min" That means your book's saved successfully.
As long as you have an account with us, you can find your saved photo books under "My Photo Books" in your account. They'll stay there for you to access whenever you want. But if you decide to delete your account, your saved books will go bye-bye too.