Yep, it's definately something buyers should check. I've purchased 3 used remotes over the years. 2 of them have serial numbers, 1 didn't ... but at the time I bought them I didn't even know the things had serial numbers under the battery compartment let alone it would become a future issue when URC pulled the plug on live-updating.

I think the moral of the story is that regardless of how you buy the remote (AD, non-AD, used) make sure you'll get the version of the s/w you want before you buy and then cross your fingers.... *grumbles*