I just used up the last of the 2004 dehydrated tomato powder last winter. No loss of color, flavor etc. They were stored in recycled food grade plastic containers with screw on lids. The containers are white, so labeling is easy. I added a line of packing tape around the lid/jar seam and stored them in an unheated outbuilding in a windowless room. (cool, dry, dark)
Storing what we eat and eating what we store; is the only way we have found to deal with storage, inventory rotation etc issues. The maximum shelf life issue is for things like dehydrated potato. If a couple years from now we are blight free, and all that would take is a low rainfall year; I will be disinclined to be using dehydrated potatoes. Storage potatoes are way easier, particularly when we have the coldroom storage space for them. Then I will shrink wrap the containers to guarantee air tight for the longer term and label with a best before date.