Hello, my name is Rusty. When you buy a book, it is stored in your Amazon cloud. They will stay there indefinitely. You'll have to go to your archived items to retrieve the books to your Kindle.
Scroll through the list of e-books, documents and collections using the 5-way controller and page-turn buttons, and select "Archived Items." Select the e-book or personal document you want to retrieve from your Amazon.com library using the 5-way controller. The content is retrieved and downloaded to your Kindle.