Somebody, years ago, recommended that, in addition to hanging a tag in the tree, burying one at the base of the tree... like, on the north side. That way, if it blows off, or the deer eat them off(b@sta@rds ate almost every aluminum pop-can tag I put on my pears), you can ID the tree. Wish I'd followed that lead...
I've got a set of old 5'-wide aluminum Venetian blinds, with baked-on enamel paint, brown on one side, white on the other. Probably close to a lifetime supply. I write on the white side with pencil, scribe the name through the brown paint on the other side with a nail... it'll last longer than I will.