Quick Epsoma question

Hey everyone!
How long does Epsoma last when mixed into soil, but not used?
I have an 18 gallon tote I filled up with some of my last rounds soil (first time recycling that specific soil) and added 4-1/2 cups of Plant Tone (5-3-3) into it in the middle of July.
Is it still in there? I assume so, but don't know. I've been mixing it up every few weeks.
Planned on using it sooner, but didn't... using it soon, though!

Oh, and, I now know I didn't need to "cook" it...

It's still in there and the extra time has made your soil better than it would have been in August.

Good deal! Thank you!