Somewhat related to managing my growing Kindle device library, I recently ran into the six device limit on a Kindle book. While I've had many Kindles for years, I rarely read/load the same books on them, so this was a first. That time removing the book from another Kindle and even re-syncing from menu and trying a couple of times didn't help, I actually had to - for whatever reason - de-register one device to get the book freed for a new installation, which worked.
Anyway, today I decided to test how I'd fare with book removal/license freeing on the second go. I loaded The Hobbit onto six Kindles that I registered to the same account: PW1, PW2, $69 Kindle "4B", DXB, Kindle 3 Keyboard and $79 Kindle "4S". This went fine. All were loaded through the device Archive/Cloud items, while connected via 3G or Wi-Fi. Then I tried to load it onto Kindle 2 via 3G - the seventh Kindle - and got this screen:
Bigger image:
http://img32.imageshack.us/img32/3307/8r3o.jpg
Then I went back to the $79 Kindle "4S", removed the book, re-synced from menu and re-tried on the Kindle 2. It worked! Now trying to load it back onto the $79 Kindle "4S" got the same error as above. I removed the book from the Kindle 2, re-synced, re-downloaded on the $79 Kindle "4S" and again it worked. Then I removed the book from the $79 Kindle "4S" but did not re-sync, now Kindle 2 refused to load the book with the same message as above. Re-synced $79 Kindle "4S" and then the book loaded to the Kindle 2 again.
So, this time removing and re-syncing worked in freeing the book license. Removing without re-syncing from menu didn't work. That said, last time, with a different book and slightly different set of Kindles, removing and re-syncing did not free the license - and I tried a couple of times back then too, no help. I don't know what was the problem then, was it the different book, the different time, the different Kindle setup or what, but that was the experience then.