Forever! I read somewhere that when properly dehydrated, beets will last up to 33 years. That's forever to me! However, I always try to use them up within a couple of years. The most important thing is to make sure they are completely dry. If there is any moisture left in the homemade beetroot chips, they are susceptible to growing bacteria or mold. It is also important to store them correctly so they don't absorb moisture from the air. I like to vacuum seal my dehydrated beet chips, but you can store them in any airtight container. You also want to store them at room temperature.