This taco seasoning mix, if stored properly, can last for up to a year. Store it in an airtight container in a cool and dark place and away from moisture. While spices don't actually go bad if they are stored properly, they do lose their potency. Make sure that the spices you use aren't stale, check this by rubbing a little between your thumb and finger, if no aroma is released, it's time to replace your spice.