That way, folks will know at a glance that it's something they might be able to play in, even if all they have is the free Demo.
So how about some sort of a shorthand code in the game announcement, like:
Dungeon Crawl [FLx5]
...meaning the GM of that game has 5 Floating License slots available for freeloaders... umm, I mean for people that are still evaluating the Battlegrounds software for possible purchase.

Does anyone else think something like this might be useful?