I don't see this said exactly so here ya go...
You do not have to PAY for a high score...that said, keeping CC and LOC open (with a $0 balance) can improve your score because it adds to your mix and shows you are responsible. However, no one is saying you have to pay interest to keep your score high so hopefully that's clear to you.
You can keep your score high by:
paying on time
having a good mix of products
having higher CL (and low or no balances)
having a long credit history
your score is NOT impacted by:
your salary
your location
your spouse (unless you co-own accounts)
whether you pay in full or pay interest (but low balances is good so if you have to pay interest, that isn't good)
your sex/race/etc
hope that helps! Keep reading the forums and asking questions, it'll all become clear
