Yes, most beers brewed in the US need to be refrigerated. To store a keg of beer at room temperature it needs to be pasteurized so it will not spoil and most beer brewed in the US is not pasteurized. A typical keg needs to be kept between 36 and 38 degrees to maintain freshness and flavor.
As days go past the freshness reduces. In general, the fresher your keg draft beer is, the better it tastes. Keg beer will remain fresh if dispensing with CO2, while maintaining the proper temperature and pressure: For non-pasteurized draft beer about 45-60 days. For pasteurized draft beer about 90-120 days.