Susan Weston agreed

A fair housing attorney friend I know says that this is perfectly approppriate for ESA's and at the time of lease renewal.

What state are you in? Different states different regulations. I’m some instances you can verify if the need is still there but it’s a slippery slope that more than likely you will lose. Make sure your rules are according to need and treat an service/support animal as you would a live in aid. Are they unruly and aggressive and it is never up to us to determine the need. You can always remove the care giver if they cause issues but more often than not, the need will always be there.

I require updated proof of vaccination, city registration (it’s annual) and updated ESA letter from provider at renewal.

No, once it’s gotten certified it doesn’t need to be done again.

In FL, I believe you can require update annually.