I have added my key manually to my windows registry and I didn't have any problems since.
how to:
First, restart your pc and do not launch the game or the cRPG folder. Just go in your steam library => mount and blade warband => right click => view cd key and copy it.
-Click on the windows key or open the windows start menu and writte "regedit", click enter or click on the program.
-On the left panel, navigate to: HKEY_CURRENT_USER/SOFTWARE/
-Select the folder called "MountAndBladeWarbandKeys
-On the right pannel, verify if you see a "serial_key" value ("serial_key_nw" and "serial_key_vc" are something else, don't care about them).
-If the "serial_key" value is missing, right click => new => "chaine value"
-Name the chain value "serial_key"
-When the chain value is created, double click on it and put your game key in "Value data"
-Click ok and close the regedit program, start the game, enjoy, rage.
i memorized my cd key because of this
also are you telling me YOU don't get tons of screaming nagging annoying boxes from steam telling you about CD keys every time you start up a videogame
You can check the little box to don't get them anymore.