Help me please, i have to type in my serial key, every time i loggin' Crysis 2 multiplayer, how can i save it, so that i dont have to type it in each time i launch the game?

this worked for me. First, type that 16 digit code in http://www.gamesas.com/redeemcode/
after it said it's activated, try 20 digit code in game. I spent an hour.. and this worked for me.. I hope it's same for you.
I bought over steam BTW.

Help me please, i have to type in my serial key, every time i loggin' Crysis 2 multiplayer, how can i save it, so that i dont have to type it in each time i launch the game?

There is an activation.exe file in the crysis 2 folder. try with that. If not Dont quit the game xD

After you type it in, join a few matches. It should stick after that.

Same problem, i bought through steam as well. Tried the activation.exe says I've got 4/5 uses left, and i'm activated.

Also tried the website linked and it took the "LE bundle" key will not take the longer one (as you said use the 16 digit, but had to try), and it still doesn't help.

I can add the key every time, but it will only allow me to see the browser. Trying to join tells me my key is in use.

Sent a message to support

I hope it sticks after I play a few matches. I was getting annoyed at entering it every time I tried to redeem my code.

@ saturns2k
Thanks for that link up above. It worked better than using the in-game link.

Same problem, i bought through steam as well. Tried the activation.exe says I've got 4/5 uses left, and i'm activated.

Also tried the website linked and it took the "LE bundle" key will not take the longer one (as you said use the 16 digit, but had to try), and it still doesn't help.

I can add the key every time, but it will only allow me to see the browser. Trying to join tells me my key is in use.

Sent a message to support
Hey i'm havin' exactly the same issue, when i'm trying to connect to the server it tells me that my key is already in use... What a hell? Do i have the bad serial-key?

Run the game as administrator will solve this

The solution for me was here : http://www.gamesas.com/forums/viewtopic.php?f=20&t=11188