I have been told by a compound chemist that the active ingredient does breakdown over time ... but really, in the younger years, 2 years out of date and still was going strong.
I’ve heard of people using gear they’ve had for 5-10 years with no issues. I’ve used some that were a few years old with no problem.
My only concern with be the carrier oil going bad. I believe it would smell off as mentioned above.I’ve had some in gso a few years past the “expiration” and the oil seemed fine. Draw some out and give it a smell.