I think this was asked last week, I stamp a 2 year exp. date on my vials and orals. If you’re buying say Test E today from me you’re most likely getting stuff that was made within past 30 days. Sometimes I’ll make a batch and sell half of it within same week.
They’ve been proven to last over 10 years with minimal degradation but YMMV. Store them in cool, dry, and dark place and they’ll be good for a 2+ years.