Most draft beer brewed in the U.S. is not pasteurized, so it must be kept cold. The temperature of non-pasteurized Ale and Lager type beers must be maintained between 36-38°F.
Keg beer will remain fresh if dispensing with CO2. While maintaining the proper temperature and pressure, non-pasteurized draft beer stays fresh about 45-60 days; pasteurized draft beer about 90-120 days.