FUEL

try to contact the creator, if there are no response just mark it not received after 7 day.

Thx

Contact GA creator and thell them about the situation. Depending on what they will say, you can:
a) agree to delete the giveaway without getting anything
b) agree to delete the giveaway and if the GA creator will be a nice person they might give you something instead
c) wait until GA creator will give you another key (if they will say it is possible)
d) wait 7 days and mark as "not received" and move on in a case GA creator won't respond or they will try to give you a key for another game without deleting the giveaway

Once again: don't take a key for another game if GA creator won't delete the giveaway, otherwise you will be in trouble.
Also please change discussion category to "General" :)