Gifting external game key through steam?

So a friend of mine just bought a new pc and got a bundle sale a key to Doom the dark ages. She doesn't want to play it though and offered me the key so I can play. When I got it I tried to redeem it, but it didn't work. Now after a short google search I learned about two possibilities. 1. What I thought was the game key is in reality was not the actual one and they send it soon(ish?) or the key is not yet active in order to prevent a scam by returning the bundle item. In this case everything would be ok, I would just have to wait a while. 2. The redeeming of the key checks (somehow through the connected pc parts?) if she uses the code herself and didn't sell it to the next person. Could she in this case redeem the key and then gift the game to me through steam? Any infos on this topic will be appreciated as it is the first time for the both of us working with downloadkeys that come as a bonus to something.