When I first started making the treats I put some in a plastic zip-lock baggie, dated the bag and put it in a cabinet -- that was two years ago and the treats look as good as the day I first made them. That was my very scientific experiement to determine shelf-life.
The treats that I sell and are, of course, fresh made. But as far as I can tell if the treats are kept in a dry cool place, they will keep indefinitely.