FYI; I believe that all gift codes are good for a year. So anything you buy should be redeemed within a year of the purchase.
Wait, what the fuck? Your gift codes expire
I'll recycle Roman5's attachment from earlier in the thread: http://static.gog.com/upload/forum/2012/12/e76e602be3d6d90f16f6fb10c132517ce88e0fcf.gif
NOTHING that I've been able to see, either in the process of purchasing a gift, or in the emails you receive afterwards, suggest that this would be the case, and there is NO sane reason for GOG to expire them -- that is an evil and user-hostile practice, and I'm horrified that you are doing it.
Not all gifts are bought for immediate usage. For instance, I have a copy of "Thief" sitting around to give away to someone some day (for unknown values of both those variables); and the recipient of a gift could easily forget all about it, and then be reminded of it some time after the expiry date.
Expiry dates for gift vouchers are wrong. They're just wrong. Don't do it. Stop doing it!!
Dude, chill, if this ever happened I'm sure a simple email to support would fix it for you. Seriously, how often do you think this actually happens?
The only reason this would ever matter is if you intend to stockpile games going off GOG in order to make rather lopsided trades for years down the line.