There are kinds of gift cards which people buy, and there are laws governing them. At the federal level, there is the CARD Act of 2009 which in §1693l–1(c) says
it shall be unlawful for any person to sell or issue a
gift certificate, store gift card, or general-use prepaid card
that is subject to an expiration date.
but it does allow an exception if
the expiration date is not earlier than 5 years after the
date on which the gift certificate was issued, or the date
on which card funds were last loaded to a store gift card or
general-use prepaid card; and the terms of expiration are clearly
and conspicuously stated.
However, a "card" or piece of paper which entitles you to install free software would probably not satisfy the legal requirements of being a "gift card" in this sense. As I understand the situation, you purchased a piece of computer hardware, and as a promotional bonus they allowed you to install a game. The terms of the law are defined in subsection (a). A "General-use prepaid card" is among other things "issued in a requested amount", and not "for a specific thing". A "gift certificate" is likewise "issued in a specified amount", as is a "Store gift card". The definition excludes "loyalty, award, or promotional gift card", which is what you seem to have been offered. If you had purchased a certificate of some kind that entitles you to get this software (not gotten a certificate in connection with buying something else), then it cannot expire in less that 5 years, and the expiration date has to be conspicuous. But that law does not apply to "bonuses" that you get when you buy another thing.