I have nitrous that has been in a bottle for almost a year and a half, is it still good?

 

I bet it's fine.......A friend of mine had an old tan (huge) 20 lb NOS brand bottle that had been sitting full in his garage for almost 10 years.......I blasted through every bit of it......It felt every bit the same as new

 

no shelf life.......should be as good as new.......