Having watched your previous posts on similar matters I am seriously wondering if adding so many restrictions is actually going to damage your business. What purpose would a limit like this serve. You should write out a terms of service for users at your cafe and if they do not abide by them they can be banned without warning if necessary. Just state that if they are banned they will not get a refund and such forth. That way if you see them doing "bad things" you have the position as you notified them about it to remove them. You could make it so the systems open a notepad doc or similar on booting stating all the cafe rules if needed.