I would love it if the system were able to stop a customer from buying a membership when they already have a membership. Our most recent example - we put a freeze on a membership, the member decided to come back early so they went online and purchased a membership. That only produced two memberships and I had to figure out how to fix the error. If the system would stop them from purchasing a membership if they already have one, that would be ideal.
If it could do the same sort of thing with punch cards... looking to be sure the last punch card was used up before allowing them to purchase another punch card that would be great.