Pipe tobacco is a lot easier to store than cigars, which have to be kept at 70 degrees F and 70% humidity. But the ideal conditions are the same. Freezing is a big no, since the dry air just destroys the leaf. Tobacco in vacuum-sealed tins can last forever - people "cellar" it because they think it improves in flavor over time - often it does! In jars like this it's probably good for a couple of years. If they dry out I just sprinkle a few drops of distilled water in and shake them up.