I used to buy freeze dried foods from Mountain House. Mostly because a couple of their items were very delicious and easy to prepare and I liked to take their stuff out camping.
Moisture shouldn't be a problem as long as the items are kept sealed in their container, at least not in the under 1-2 year lifespan. When you open the package moisture is a big deal at that point. Typically you'd want to use the open product within a week or two.
But really you're paying a premium for the freeze dried food. $500 for 6 months is cheap
and I bet it tastes like cardboard with bare minimum proportions. Cheap
food isn't really cheap if you never eat it.
You might consider just changing your normal diet towards using shelf stable cheaper foods. Rice, dried beans, pasta, canned meats, clarified butter, potatoes and other roots, dried milk, canned fruits, flour for making your own bread, jams/jellies, etc.
Living without refrigeration
was the "norm" for human existence up until recently and there's a lot of good nutritious and delicious options for provisioning
along those lines. No need to be eating peanut butter on stale crackers for dinner.