Using Expired Grow! ?

Hey all:

I found a tub of chocolate Grow! powder that I had stashed under my desk at work recently that I had forgot about but when I checked the expiry it reads 05/06. There is still almost the full tub & I guess I did not finish it & forgot about it since I was still finishing off the vanilla tubs I had.

Good or not to just finish it off or just pitch it? How long does this stuff keep anyways?

Id use it as long as it has been kept dry not caked etc