Game already own. Why doesn't it show up?

have you resynced you account ?

It's a DLC, steam api doesn't work well when it comes to DLC's, so no, your not going to get suspended.

Yes I have but it still doesn't show up.

So is it possible to give the key to someone else even if I already confirmed that?

DLCs Wins that appears as not activated
Steam API has problems identifying some owned DLCs, so the following ones are probably activated!
Show me those DLCs!
Vanguard Princess Lilith (2017-09-17 21:59:00)

From SGTools point of view, you are in the clear. As many more users ( =
Not to worry.

I didn't even know I had the same DLC, as the list wasn't filtered or it didn't show up in my list or... I don't know. I know I already own it and I didn't use the key I won. I can keep it or share it with someone else if possible.