I'm a lawyer and have maintained my bar membership, though on inactive status, since FIREing 3.5 years ago. Every state and country is presumably very different, but here I was able to put my membership on inactive status and don't have to do any continuing education, but cannot practice law at all, even pro bono. Which is fine, as I haven't been pulled to do it.
I was kind of surprised that inactive status is the only option for retirees that don't want to completely resign their bar membership. Even with a 50 year career in the law (which I did NOT have!) you have to keep paying till you die. That's the guild system for you! The good news for me is that the annual payment is less than $150 and given how hard I worked to get the bar membership in the first place (the bar exam was an interesting experience, but not one I will be repeating; and that's only one element of gaining bar membership), I haven't considered resigning so far.
But actually, this year I was thinking of doing so. Why keep paying when I feel so confident I won't practice again? OTOH, I can see that $150 is actually a bargain compared to some other professions, so now I'm leaning a little toward just keeping it for now.