There was a somewhat recent change that "on-device testing" only requires a regular Apple Id account (and you even get the privilege to report bugs for free to Apple! /s).
Only works for up to 8 apps per device installed at the same time (which sucks for my case because I have dozens of small demos to test).
But yeah, those "on device testing apps" expire pretty fast if I remember correctly (I mostly just debug on the simulator these days).
Also see (search for "Benefits and resources": https://developer.apple.com/support/compare-memberships/