Starting with version 2019r2, ArcGIS Online service credits will be required to perform certain tasks when Esri’s ArcGIS World Geocoding Service has been set as the system default geocoding service within Lucity.
There are many tools, services, and applications provided with Lucity that use a geocoding service. Some of these tools will take the results of the geocoding service and store them in the Lucity database. It is this action, saving the results of the ArcGIS World Geocoding Service to the Lucity database, that will start using your ArcGIS Online service credits.
More information on this change including what actions, if any, you should take when preparing for the version 2019r2 upgrade can be found in this knowledge base article. Please contact a Lucity support representative if you have any questions or concerns related to this change.