I still have product keys for this game, back from when I pre-ordered the Admiral Edition of Endless Space in 2012. I never knew where to enter them, so they just sit around and pop up whenever I open the game. Not sure if I'm just having trouble finding where to input them, or if they are no longer valid. Any advice or solutions would be much appreciated.

Have you linked your profile here with Steam? Should auto add all your keys.

I have, I just am not sure what sort of changes I should be seeing.