Beer may stay up till six months. If you store a chilled beer unrefrigerated then it may last only for couple of hours. But if you intend to store it for longer, then it should be kept in the freezer. If the beer is stored properly, as in, under cold temperature and away from sunlight then it can stay good for longer. Though it is said that if a bottle-conditioned beer is stored properly it stays good for up to 5 years, but the truth is, its taste starts changing after few months itself. Only if you opt for beer with high-content alcohol then it may stay good for up to 5 -10 years.