It shouldnt matter. What do you mean you cant play together?
If you go on seperate computers on seperate accounts, add friends on MP then you can play together
![Smile :)](http://gamesas.com/images/smilies/icon_e_smile.gif)
The CD-key is only for activating the game, whatever you do in-game doesnt matter, and shouldnt effect the CD-key.
And by the way, if you do buy the game and get a different CD-key it doesnt matter. Your account will still be there and you will still be lvl 33
Just to note, each CD key has a certain amount of times that you can use it before it exceeds the limit, then you will have to contact EA customer support to let you use the cd key again but once EA let you use the key a few more times they wont let you use it anymore.. because i think its like 10-15 uses, so they will get suspicious or something if you keep redeeming your code
![Razz :P](http://gamesas.com/images/smilies/icon_razz.gif)