Ricotta cheese can last for several weeks when stored correctly, however it can spoil quickly if not taken care of properly. To preserve ricotta cheese, it should be kept in an airtight container in the refrigerator, and eaten within two weeks of purchase. To tell if ricotta cheese has gone bad, look for signs of mold or off-smelling odors. To keep ricotta cheese at its best, avoid leaving it at room temperature for long periods of time and be sure to use it before the expiration date. With proper care, you can enjoy the delicious taste of ricotta cheese for weeks.