I keep my supply of epoxies at room temperature and I believe they will have
a very long shelf life; years if not decades. Of course, for any critical
bonding application, you should do a simple adhesive test to confirm it's
still good before proceeding. Using epoxy before its expiration date is
always the safest course, if not the cheapest.

Keeping some types of epoxy at cold temperature, such as in a refrigerator,
will cause them to crystallize. The crystallization should be reversed by
slowly heating the jug of epoxy in a pan of water until the crystals
dissolve before the epoxy is used.

Dennis Johnson