This past summer I finished up loading some GreenDot and RedDot powder in 12ga I had originally bought in 1967. It was bought in bulk at that time (coffee cans) and was stored in them plus wrapped in plastic bags and tied shut. Stored in several different places over the years but always away from high temps and humidity. It worked just fine. Ammo dated from WW1 worked fine also as it was stored well too. Improper storage will kill it in short order. Properly stored, it's shelf life is more than our lifetime.