Seems a Logbook of the World (LoTW) “certificate” has to be renewed every 36 months, as at the end of January an emailed notice arrived saying:
According to our records, your ARRL Logbook of the World Callsign Certificate for:
K9ZW – UNITED STATES OF AMERICA
expires at:
Feb 9 16:39:02 2023 GMT
To continue submitting log data for this call sign and entity, you must renew your Callsign Certificate. Renewal is quick & easy before your Callsign Certificate expires; if your Callsign Certificate expires, a new one will need to be requested.
Instructions for renewing can be found at:
73,
The LoTW Team
Apparently ARRL’s LoTW has a window, where you won’t be told you should renew until there is a tight window, which is you do not renew before that deadline your certificate cannot be renewed. If you go past the deadline a different process creating a new certificate is required.
Doing the process is easy provided you can access your TQSL program and your certificates. I got an immediate popup noting my certificates were in the expiration time frame window, and asking if I would like to renew them now.
Here are some screen shots of the process:

One of the several confirmation of data screens

Screen indicating the request was completed

Looking at individual certificate locations – they say “Awaiting Response”

The email confirming the rest was received at LoTW
A day later I received notice that my certificates successfully renewed, and how to install the updated certificate.

The renewal confirmation with new certificate attached
The link for renewals si:
https://lotw.arrl.org/lotw-help/renewing/
Small critique that the short window presumes you are available before expiration to manually start the process from your TQSL computer. I’d expect more than the occasional ham finds themselves away for the renewal period. Unless you have made preparations to have TQSL fully set up with your certificates on a portable device, it appears you need access to the actual machine. Not certain if you can remote into a machine to do the process?
A lot of what happens at renewal is reconfirming the data LoTW has for you – email addresses, locations and such.
Next renewal for K9ZW will be 2026.
73
Steve
K9ZW