According to the Georgia Egg Commission, if kept in the original carton and kept in the body of the refrigerator and not in the door eggs can last 4 to 5 weeks from the day they are packaged. Generally, eggs hit the stores just a few days from being laid so you are probably safe to use them for a month after you purchase them. You can tell that the eggs are getting old because the whites will be watery and the yolks will be flat. They are still fine to use in cakes and mixes but probably won't make for pretty "over easy" eggs for breakfast.