I have Sitecore 9.1 instance and today my sitecore license file expired. I had to replace the license.xml in multiple places to make sure my site, xConnect and Identity Server sites work.

Sitecore site: The /App_Data folder

xConnect site: /App_Data /App_Data/jobs/continuous/AutomationEngine/App_Data /App_Data/jobs/continuous/IndexWorker/App_Data /App_Data/jobs/continuous/ProcessingEngine/App_Data (new to Sitecore 9.1)



Hope this helps if you have license expiration message.

Happy Sitecoring!