You may play six games, not more. Just if you subscribe (you get your "pawnstar" ). When you play chess here this causes costs for Russ & Chris, the site admins, they have to pay for the server traffic. 20 USD is not very much: get your pawnstar, it is the money worth!
PS: Russ is planning a mentor system where nonsubscribers can play (perhaps) more then six games. You can read more about the ongonig discussion in this forum.