@tzxsean - The person didn't check the code or intentionally give you used/expired code.
To everyone, you can always keep a promo code, check it if still valid or not using the redeem section, just don't put your password

You can check it many times, if the pop-up box appeared then the code still valid.
If you received a gift from dev - by email, you can extract the code too - copy link

Then you can carry around the promo codes, use it with other account or give it to someone.
Gift usually like this, green background! This kind of codes they generate using credit card~ Yes, you can extract the codes, give it to someone or use it directly. Use copy link.

Promo codes generated/requested from Apple only using plain white background

This kind of codes, only available if the dev requested from Apple, usually during updates, price dropped or price increased.
This post has been edited by korn: Nov 26 2010, 09:39 PM