Parmesan is a hard cheese that can be kept for long periods. It is important to keep it properly to maintain its quality and flavor. It is generally recommended to keep parmesan in a cool and dry place, such as a refrigerator or a cellar. It can be packed in a parchment paper or in a plastic bag to prevent it from drying out. It is important to note that parmesan is a hard cheese, so it should not be watered in the air because it needs a little humidity to keep its texture and flavor. Parmesan can keep for about 6 months in a well closed refrigerator, it can even keep longer if it is well preserved, that is to say in a cool and dry place. It is important to regularly check the condition of the cheese and throw any song that has signs of mold or deterioration. If you buy parmesan in pieces, it is better to grate it yourself just before using it to enjoy its optimal flavor and texture.