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
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:
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.