The lifespan of cheese depends largely on its type as soft and processed cheeses stay fresh for one to three weeks after opening, while hard or unprocessed cheeses may retain their quality for several months after purchasing. Generally, natural cheeses that are not processed and cheeses stored in chunks, rather than shreds, stay fresh far longer than their softer or processed counterparts. Although many cheeses come with "best by" dates, proper handling and storage techniques may either shorten or lengthen the lifespans of cheeses.
Regardless of type, all cheeses should stay in the refrigerator at a temperature between 35 and 40 degrees Fahrenheit. After opening, wrap the cheeses tightly to eliminate excess air and retain texture and flavor. Exposing cheese to air invites the growth of mold and bacteria, which may shorten the cheese's lifespan. Cheese also picks up flavors of other foods easily and should be isolated from other strong-smelling foods in the refrigerator or freezer.
Cheese loses quality shortly after opening, but unopened cheese may last for several months, provided the refrigerator temperature is less than 40 F or the freezer temperature is 0 F. Sometimes, cheese develops small patches of mold after opening. Mold on hard cheeses does not pose a safety threat, but remove a one-inch square around the spot. Mold on processed cheeses may present health hazards, however, and soft cheeses with mold should be discarded.