I have tried plenty of my own expired prohormones from trusted brands that I had great success with in the past. I go to use them a few years after expiration and it is considerably less potent in my experience. A general search comes up with this:
List of prohormones and their shelf lives after expiration date (only works if you preserve properly) :
Halodrol / Promagnon : 1 to 3 years
Epistane / Havoc : 6 months to 2 years
Tren (Trenavar, Trenazone and derivated) : 1 to 3 years
Protodrol & any cutting prohormones (stano, p-stanz, etc.) : 1 to 3 years
Bold (Boldione) : 1 to 3 years
Phera / Superdrol / M-Sten : 1 to 3 years
Mine were not vacuum sealed, or placed in a fridge, they were just kept away from light and extreme temperatures in a cabinet.
Personally, I would only consider taking an expired prohormone if it still has its original seal...and is no more than 1 year past its expiration date.