I was wondering this same question, so I contacted several manufacturers about it. Even though some recommend a shelf life more importantly they all recommend storage conditions.
Keep this type of thing in a cool dry place that is not prone to temperature extremes, meaning something like a basement or controlled atmosphere as best you can. It "doesn't mean in the garage" where it might be 110 degrees in the summer and 0 degrees in the winter.
Container seal is the difference between it being any good next year or 5 or more years from now! Take the time to seal it correctly without beating the lid into oblivion.
These are just common sense instructions really, but, I wanted to hear it from the Manufacturers, so there it is, just as Accumulator advised.
Changeling