3 paid accounts? Your wording is somewhat confusing.

If you want to play on the Ps3, there's no need to activate the account you get with the game there (assuming it works like XI did). You just need the game files, then you're good to go with your own accounts.

If its 3 paid accounts, you have to select which account you want to log in with. You could do Account1 on PC and Account2 on PS3 etc.