Properly packaged, it should last a couple of years.
It will darken with age, but doesn't seem to affect taste. Opened it will darken quicker.
If it is in tins, it seems it can pick-up a metallic flavor. No experience, just what seems to be reported. However, just like tinned vegetables, it should last a long time.
I buy it in 33 lbs HPDE containers, and it usually lasts 2 to 3 months. After opening I keep it in the basement, and usually don't have a problem with it.