TQ shelf life

I have a few bags of tender quick that were purchased two years ago and there is no expiration date on them. I am curious if anyone knows if there is a shelf life for it as I'm thinking of doing a bunch of BBB for holiday gifts this year..thanks.

Thanks Mark, I was thinking that the salts should keep for quite a while but I wasn't sure. I have had the bags stored in an airtight plastic container and they havent clumped up yet.