no you don't have to pay for anything all you do is register the only thing you have to pay is for add on for a game, for example if you buy a racing game and they decide to add more cars to the game their will be an option for you to go to the playstation store and buy your car. you can browse online with the ps3 for free.....not sure what the other guy talking about playing a game online......i know you can buy game online but don't think you have to pay to play....i got a couple of ps3 games and i don't pay anything to play......but i don't have final fantasy.......these are the game i played online and haven't paid a cent. sorry warhawk is another online free game i play warhawk a bunch and the only thing that is an option is to buy the additional maps and plane, but there a lot of people who still play the maps that are free...so enjoy your online gaming!!!!
Ps3 is free. It's only Xbox that charges for playing games on line.
Having said that, some games you have to subscribe too - Final Fantasy online is one of them, there is a monthly subscription for this game.