Downloading book

Hello, I purchased an ebook yesterday and was advised "The download links expire after 90 days so to continue using the ebook after the expiration, you simply must save the ebook to ADOBE DIGITAL EDITIONS". However, after authorizing my computer and opening the book on ADE, it just says 89 days remaining. I should have indefinte access. How do I save the book so that I have access to it after 89 days? I am using a Macbook.