Your biggest enemies are AIR, HEAT, LIGHT. You will to get some small glass jars, line the bottom with dessicant (it's cheap and readily available as "damp rid".) then place a piece of tissue paper above the dessicant and place your drugs in little baggies or whatever above that, seal the jar and hide it somewhere in the fridge. If the freezer is not an option, then anywhere else in the fridge is OK. If you have a lot of drugs then an old used wine cooler on craigslist might be a worthwhile investment.
The chemical should never be close to heat, it should never see a single photon of light, should not be touched by air/oxygen. I have had MXE stored for years with no noticeable reduction in potency just in glass jars in the freezer. I also stored acid and other valuables similarly with no problem.
Somebody might toss out that box.. you're best leaving it somewhere AIR tight (meaning glass - no other substitute) or even glass within glass. a dozen big mason jars will cost $12 but *any* airtight jar will suffice. Low temperature, away from light and moisture, and airtight glass means you can store your drugs for years with no issues. I do. I let friends borrow drugs and after a few weeks they were moldy.. such a waste.
