I stored mine at room temp for several years. All the red stuff eventually precipitated out and settled to the bottom. I bought some fresh stuff on Amazon but it hasn't arrived yet. The red precipitate is soluble in alcohol, but the consensus seems to be not to use alcohol.
Do not ever mix DB with alcohol. Just stir or shake to mix in the sediment back into suspensiom. Even without the sediment the clear liquid works as does the sediment as a paste. Store at room temperature. As yet I have not encountered a shelf life that prevents the intended use on plants, in fact aging is important.
Thanks for the tips! Good luck with yours True North. Like I said, my DB from Amazon seems to work just fine. I have only had to use it a couple times though, and not on anything that was very far gone.