BTW, despite the recurring denial in the series and movies that there is any type of currency, there are several mentions of "credits". Then there's Kirk saying, in I think Undiscovered Country, " I just bought a boat". With what, if there's no currency? I know it's difficult to maintain a long running fictional universe without creating contradictory situations in the canon, so I accept it and keep suspending disbelief for the sake of the good parts.