After I read about it here, I bought a tube of 3M Fire Barrier
Sealant, but when I got home and read more I decided it wasn't what I
want.

I put it in the car to take it back and didn't think about
temperature. It was there for 2 days, all of it 30 or below and last
night was 10F.

Am I obliged to keep the stuff and try to find a use for it?

The tube itself says to "store between 40 and 90F for maxmum shelf
life."