If your shrooms have been dried properly, you can store them for years in an airtight container. Psilocybin is sensitive to oxidation, so I would keep mine in airtight mason jars. You can also put dry ice inside the jar (make sure it's the kind that's safe to use in beverages) let it fully evaporate, and then seal in your goodies. This works wonders, though if you're only storing them for 6 days the fridge would probably work fine.