7-Day Free Trial--Or Sony Scam?

Well when i bought the game i just couldnt get enough money for the frist month (cna u belive it?) so when u get the game there is a cd case it has 3 cds and 1 7day free trial, and the acct keycode is on the front. so i mad a new acct and clicked on planetside and it says "what is the method of paymet for playing planetisde"? it has either gamecard or payement, i clicked game card and typed in the key for the free 7day trial u get when u buy the game (found in the cd case) i didnt realize u are asspose to give that to a freind then they buy it. so now when the 7 day free trial is over i go to subscribsions and it says the 7 day trial is over so i click that and it says Please enter in your acct. keycode. but i already used that acct code when using the 7day free tiral. and i dont want to go out and buy the game a hole nother time!!!!! so plx help me. i think this is a scam for u to buy the game again.