You do not have to order a photo book with the exact number of pages that the credit states: the credit covers a book with up to that amount of pages, so even if the finished book has fewer pages the credit will still be used and cover the cost of the book, excluding delivery.
You can also choose to add extra pages to your book if you want to, and just pay a small additional fee per extra page depending on the book type.
To see how you can redeem your credit, please watch our video: