License not returned by club?

My 20 year old son went to a club last week and was asked for ID. He produced his license and gave it to the bouncer who looked at it and said that he would have to hang onto it for the night (for whatever reason) My son is not driving for the moment because he is going to university and lives on campus so doesn't use the license very much at the moment and he forgot to get it at the end of the night. About a week later he realized he didn't have it and went back to get it and the club said they couldn't find it. So my son is without his license. What sort of legal problems could this cause for my son? Could the information be used for anything?What can my son hold them to? Help!....thanks in advance