that is why I don't buy anchovy paste. LOL. I have never seen an expiration date on a tube of the paste but I think it has a lot of salt in it and if is kept refrigerated it will last a while but I think good common sense it always in order.

In my experience, if tightly capped it lasts a long time. I've used anchovy paste for many years. Occasionally a tube will "disappear" (or maybe it's just hiding?) in the fridge. I've never had a problem with using an opened tube that's been around for even five or six months. As Mr. Hirshfeld astutely pointed out, it's mostly salt, which for centuries (millennia, actually) has been used to preserve foods for months and even years. ;o)

If your anchovy paste comes in a metallic tube, there's pretty much no air getting into it at any point. This, combined with the salt content, assures that it'll last a very, very long time.

Every time I've purchased it, The expiration date for the tube is on the box. I keep mine in the box, or you could write on the tube

Not an expiry date, but stilltasty.com recommends 12 months open for best flavor. After that, ok to use, with some lessening of flavor.