By methodically working through this guide—starting with the Sentinel service, then the firewall, then the license file—you will resolve the issue in less than 15 minutes.
: Aspen HYSYS often uses a token-based system. If "all licenses are currently in use," you must wait for another user to close their session and release tokens before you can check one out. Network & Connection Troubleshooting Aspen Hysys License Checkout Failed