Hey! Sometimes key redemption issues occur due to system errors, etc. It's not common but we do have a limited pool of support keys for users that encounter issues with the keys in question. They just need to provide documentation that they're getting an accurate error.
For the Decieve Inc. Closed Alpha giveaway, it was a closed Alpha that had a small window of being playable. As it states, the Alpha closed on November 13th. If you're getting an issue with redeeming the key now it is almost certainly because the window of playability has shut off.
@ieve97 Well I never even looked at the date, I imagine you are bang on with your comment, it's odd because the keys available was still very high (over 3/4) of keys being still available - I guess not many people wanted to try the game.
It is a shame I haven't checked the giveaways for awhile as I wanted to try that one.