tinyE: gift certificates/credits
Some states even separate the two. One of the reasons why many retail chains put return credits on a gift card now.
Enebias: Now that you mention it... even here most gift cards expire after one year. That is very unfair, as they have been paid. Why imposing a limit on the use? It's not like the customer can play around with inflation and foreign coin. 1 dollar will remain one dollar, not exchangable ot usable in any other way than in a certain shop.
Not sure about Italy but here in the US, companies can't claim it as a sale until it is used. Or declared abandoned. After a year, they declare it abandoned and take the cash.
edit: When I first saw this thread, I went looking for the Polish laws but couldn;t find anything about it right off. In fact google kept assuming I was talking about New Jersey instead of Poland for some reason.