Wow. I didn't know they could take something away after you've bought it. That seems ridiculous. Even if you just rent something you at least know how long you have it for.
I was notified, by Email from Amazon, a few months ago about the Chan Book Set that I bought. Was given a refund and the book set was deleted from my Archives, not from my Kindle, because the set was still on my Kindle. Was told by the Email that the seller did not own copyright to sell this collection. I had read all the books by the time I received this Email notice from Amazon. However I still have these books stored in my Kindle for PC files on my computer. As far as I know Amazon can only deletes books from your Archives stored in your Amazon Account, not from your Kindle. I hope this helps.