The shelf life of marijuana stored in mylar bags can vary depending on several factors, including the quality of the mylar bag, the environment in which it's stored, and how well the bag is sealed. Mylar bags are known for their ability to create a barrier that helps protect the contents from light, air, and moisture, which are factors that can degrade the quality of marijuana over time.
Under optimal conditions, properly stored marijuana in mylar bags can remain good for up to 6 months to a year. However, it's important to note that marijuana can start to lose its potency and flavor over time, so it's best to consume it as fresh as possible for the best experience.