If your system has no connection to the internet, it is possible to perform an offline activation. This application will walk you through the steps to generate and implement an offline activation file: app: https://rs-support.shinyapps.io/offline-activation/
More information is available in the admin guide.
Once your activation file is in place, you can check the status of your current license with the following command:
$ sudo /opt/shiny-server/bin/license-manager status-offline