Hello Eggtooth, welcome to the forum.
There there, no need to get too frustrated. We'll sort it out!
A license key should be usable, no matter where you buy the game. And you can use the language patch to switch the game to what language you need.
Can you be a bit more specific? What are you trying to do exaclty, and where does it go wrong. And when it does, what does the error message say?
Also, if you like, you may send me the key, in a personal message, and I will check it out for you!
(Never post a key on the public boards!)
Regards,
Fred