I recently borrowed several Amazon Kindle ebooks from cabq.gov/library
for 10 days.
On the 10th day, the library emailed me, telling me my loan had expired.
However, the book in question (“Curious George and the Pizza Party”)
remains on my Kindle, and I can still read it!
My guess: until I connect to Amazon’s wireless network (which I almost
never do), the Kindle doesn’t “really” know what date/time it is, and
therefore can’t remove the book.