There's a lot of threads on here about this already, but just for your edification... I keep a half sheet inside foil, inside a plastic ziplock, inside a mason jar, at room temp, and I've had them for about a year. The hits are still as potent as the day I got them, from what I can tell. Keep it dry, out of light, and away from heat, and it should last you a lifetime, if you so desire it.