Does the money you make on Inbox dollars expire?

I have about $35 on Inbox Dollars and a full $40 cash out and then some on Receipt Hog. I'm not looking to cash them out any time soon, but I want to bank my points for when I move out in a year or two, so I can have gift cards saved up to cover some costs for living supplies. Should I cash them out and save the cards now or hold them until later as planned?