My cure is a few years old and lost the pink color. I keep it in teh cabinet in the kitchen.
I assume it is still OK .... what say you?
Personally I would use it. Nothing wrong with it.
Having said that, I store my cures in a separate room and positioned where nobody else will grab them. Way beyond the years where kids are rummaging around.
Good luck and good smoking.
In the UK the pink salt (which often isn't pink) is shipped with a best before date of 12 months. With such a long date (which is only advisory) providing it had been kept dry and sealed I would be happy using it up to about 18 months. As aeroforce100 says - it isn't expensive so why would you take the risk?