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Well fresh is always best. I do not even keep mine in the fridge. Stays in a kitchen cabinet. As long as it is not caked too hard, I would think it would be fine to use.
Before you throw it out taste it, if it tastes good then keep it and use it. If you keep it in the fridge in an air tight container it should last 6 months IMO. My rubs are all on the top shelf of our spice cabinet and they keep a good strong flavor for 4-6 months.
I make my rubs in really big containers and leave them in the counter and like Flash said if it not a big clod of goo you should be fine. After all your only enemy I think is water or moisture other then that it's just dry spices.