How long will an xbox gamer point card last?

My boyfriend wants a card for more gamer points for his xbox account, if i buy it now, how long will it last until it "expires"?|||you should buy it and reedem it in the first day or 2. It won't EXPIRE or anything but trust me you'll lose the card and P.S. use a coin to scratch for the code not a knife I've heard people $20 becuz they used a knife.|||I would not hold onto it for more than a year.|||no more then a year but he can activate it as soon as he gets it without spending it all at once