Thank you!

^^

Thank you so much!! :)

Thanks for the giveaway :)

Thank you very much for your giveaway!

thanks

Thank you very much for your giveaway :D

Thanks

Thank you :)

Thanks

Mirror's edge FTW

Thanks for the giveaway.

Oh maybe I have misunderstood you. Sorry I'm a bit slow with english :D
When you just sent the key (like an hour ago), you can just go to your giveaway, and edit the key to "nothing". If they haven't seen it, yet, then it should still be valid. But yes it could be a risk, that the key is not longer working for the next winner.