The first 9 keys where expiring the same day the giveaway was finishing, you DO NOT do something like that.
This is also one of the reasons GOG keys where completely banned and now you can't make giveaway with them, the fact that the system make a wall and you can't add them is enought as a warning about it.
GOG keys that will get the attention of moderation will be blocked, if the giveaway is still going it will become "not avaliable", the users that joined it will lose their coin, a victor will not get extracted and once finished the giveaways and keys are permanetly lost unless you have a direct link to the page.
You will also don't get any point from them.
TL ; DR
It's simple, you put a key in the form for the giveaway, if yo ucan't you DO NOT do the giveaway, you don't go around it making writing things down, no user need to read the post of the giveaway to know how to redeem it's key and until when it's reedemable.