I think what you meant was no "hard" miles expiration. Ie, while most US-based FFPs have (or will soon have) miles expiration, you can keep extending it forever with just about any "activity" (including partner activities aplenty that you can do on the ground or even from the comfort of your home). Except for some UK-based ones, most European and Asian FFPs have "hard" miles expiration, ie, your miles expire after a few years and there's absolutely nothing you can do to extend that.