According to EatByDate.com, unopened Parmesan cheese stays fresh for two to four months past the printed package date when stored in the refrigerator. Frozen, unopened Parmesan cheese stays fresh for six to eight months past the printed package date. Parmesan cheese should be stored properly for maximum freshness.
Opened Parmesan cheese has a shorter shelf life of around three to six weeks in the refrigerator. The best way to store Parmesan cheese is in its original packaging or in an airtight container to keep out moisture and other contaminants. Parmesan cheese freezes best when placed in a freezer-safe container.
Kraft Parmesan cheese is an exception to this rule. It keeps best in the pantry and forms clumps when refrigerated.