No serial key for multiplayer! HELP!!!

[mRNick]

In the box with the game I've got only the game serial key and a techsupport key, but when i downloaded the new version of M&B Warband it asked me for an other serial key, what shall I do Probably it's the multiplayer key.
P.S.
I'm not asking for the number, I'm hoping to get some idears what to do

[Armie_knock]

Where did you got the game?

[Illusive Man]

You only need the game serial key.

[mRNick]

I've got the game in the computer shop, it's a licence game. 

[mRNick]

My serial key has 5 parts, but it askes for a serial key with 4 parts

[Illusive Man]

My serial key has 5 parts, but it askes for a serial key with 4 parts

This key is made for Steam. You can download steam and activate the game, everything should be fine.

[mRNick]

Steam?! I have no connection between Steam and MB))

[Illusive Man]

Keys usually have 4 parts, but your has 5 which happens to be a key meant for activating the game on Steam.

[mRNick]

How many keys must be in the box with the game? 2 or 3?

[Illusive Man]

I'm not sure, I bought my M & B games via Steam, but I'm sure there's only 1 serial key.

[mRNick]

Don't you know someone, who I can ask? Is there some one, to who I can write?

[Armie_knock]

I bought my game in a store, but got a steam key that i entered and downloaded the game thrue steam. Pretty wierd.

[mRNick]

So you mean I need to download it through Steam?

[Leofricz]

So you mean I need to download it through Steam?

Most likely yes.

[mRNick]

Another question - how?