With one exception, I store all my paper in the darkroom. Some of it is now up to 20 years old, and some of it still work just fine. A few show slight fogging when processed normally, but turn out to be better than new for lith printing.
I have two boxes of Guilleminot G1 in my freezer, and one opened box in the darkroom. This paper hasn't beenmade for many years, so it's worth storing properly if I ever need to use it.