OK, so you travel a lot and work hard. You earn lots and lots of points and miles in the name of business travel. Do you think that you get to keep those points forever? Well, you don't. Points and miles expire after a certain set period of time. Normally, the expiration policies are two to three years from the time that you accumulate them. However, some airlines are getting more strict about their expiration dates and making miles disappear faster. Here is a sampling of some major airlines' policies on mileage expiration.