I have some H4831 that I bought for $0.52 per pound. That was back when the name was just 4831, before IMR introduced their 4831. It has been stored in an unheated building in a wooden cabinet in a metal container with a tight fitting lid. The powder, so far as I can determine, is as good now as it was when new. Ditto for some H4895, which I bought for about a dollar a pound, that also was known just as 4895, before IMR introduced their version. Ditto for some Winchester AA 473 and AA 452 which I bought in 1977 for less than $5 per pound. All of it is as good now as it was when I got it.
Remember that the original H 4831 was obtained by breaking down WWII surplus 20mm ammo. That powder is well over 50 years old now and still good. When Hodgdon first introduced what we now call 4831 it had no name of its own, and was marketed as "4350 Data". You used loading data for 4350 when you loaded it.
The original 4895 was used in .30-06 ball ammo during WWII.
Good storage is the secret. No direct sunlight. No extremes of heat. Extreme cold is no problem. Keep it dry. That's about it.