for sure good to know about the ability to exchange. tons of thanks there. that is useful, because i have just been tossing keys even when not expired. i don't always have much time to play games, and mostly have like less than a hour per day... if even that.
i suppose another idea could be to simply allow the exchange of keys for some useful goodies. expired or otherwise.
in the end i still feel it is kind of a waste, because the exchange mentioned is yet for another key that will also expire.
that could also be part of another idea... allow the exchange of multiple keys that are, or are not, expired for a key that won't expire and can stack.
but just to bring this one back up again... it would be great if, at the very least, they keys went to the materials tab of the inventory. it seems reasonable. they have pretty much the same usage scenario as Extreme Passes and Advanced Capsules. i don't see any reason to not have them categorized as materials.