a downside ( or however you look at it ) is that you can get the license anywhere else, too. - mind. handing out a license would be a matter of RP... yet still more or less mandatory to do. - it is still not upon factions to deny handing out stuff ( when it comes to making another player act against the official rules )
but it would certainly mean to "come into contact" with each buyer. that way, a faction knows the persons flying their ships ( which is the most important part there ) - so the fleet is not just a bunch of no names, but ppl that are known to the high command.