All you have to do is sit at the door checking that each person entering a function room of the convention has a membership badge. Almost all ScienceFiction conventions are thought to do this, but in fact many do not, and PenguiCon does not. Sometimes we may do so for ConSuite, but not DealersRoom. Our policy is to definitely not turn away any paying customer from the DealersRoom just because they aren't with our convention.