Once a publisher archives a book, it is no longer available for readers to download. Most publishers archive books around the publication or on-sale date, but it is entirely up to each publisher when they choose to archive a book.
Many publishers set their archive date in advance. If the Archive Date is set, it will appear in the Title Details page, so that you’ll know ahead of time. After this date, you will not be able to download another copy of the file, or access the file through NetGalley at all. If you plan to read or provide feedback on a book, we highly recommend that you download or send the book to your Kindle when you are approved.
Any copy downloaded to your computer, iPad, or Adobe-compatible reader will be available until you reach the Adobe Digital Editions expiration date, as described above. If you have used the Kindle option to send a copy of the file to your Kindle, that file will not expire, and will continue to be available to you.
Remember, you can still send Feedback to a publisher if the book is archived. More information is available here.