This person will never be a profitable customer. They will cost you far more in time than they will generate in income. Get rid of them and move on. We have a

This person will never be a profitable customer. They will cost you far more in time than they will generate in income. Get rid of them and move on. We have a recurring revenue model and only after learning this over and over that we are now very quick to cut our losses when we see this kind of abuse or "cleverness". 10 bucks ain't worth your time to mess around with this joker. They will do this again, and again. They might even email you to ask for a discount on the 10 bucks they are trying to get around paying you. Good luck!