The licensing service is a background process that must be running before ETABS is launched. If the service is set to "Manual" startup and was not triggered, or if it crashed due to a Windows Update reboot, ETABS will throw Error 120 because there is no active listener on the server port.
For detailed guides on specific versions, you can refer to the official CSI Knowledge Base or check support videos on Are you using a standalone license on a single PC or a license managed by a server? etabs license not recognized error 120 work
subfolder of your ETABS installation directory) to deactivate your license and then reactivate it. Verify System Date The licensing service is a background process that