From what I have read even here on the forums, once you remove any style of tobacco from the original tin then the aging changes a bit. That being said, if you do not open a jar once you fill and seal, I would think you could store for longer than 5 years even if a slight air exchange happens. The tobacco shouldn't dry out much and a little air at that point wouldn't be a big deal. Obviously, check the jars from time to time. Drying out or the opposite, molding, really shouldn't be of much concern unless very, very long term (in the case of drying out).