Had the same can of PAM for, I believe, 3 years, on hand to pre-treat QT tubs. Did a trade with local reptile store for an atb, it did have mites when I got it into QT and the PAM worked as normal (this was the last of it, so at the end of the approx. 3 years). I've never used anything additional with the PAM, it works great. I'm curious what you are able to find out about shelf life, would be good to know. Maybe I just got lucky!