I've got about 3/4 gallon of epoxy laminating resin that's oh...close to 20 years old now (ProSet)! Guess what? It works fine. The hardner is now brown and stinks, but it still activates and holds true to pot life and cure times.
Just kept it sealed, out of sunlight and in a reasonable, but not refrigerated temperature. Seems West systems does the same, but the pumps stop working...