Yes freezing a mixed nutrient solution will make it last nearly forever but it's ususally not practical. Some arguments against are that refrigeration can keep nutes long enough to use a second time, you can just not mix more than twice what you need, having enough to really make it worth freezing could take up alot of freezer space, teas require so little attention that they practically make themselves and also, you have to completely thaw and shake the nutes before using. I'm sure there are some circumstances where it's worth doing, though. One thing in its favor is that plants don't feed on the complex compounds that we do, which can be destroyed in the freezing process, and so freezing doesn't affect the nutritional value much for the plants.
