To make your on-premise Visual BACnet Enterprise work, you will need to get a License key from Optigo.
Once you have this license key, navigate to the "settings" page on the menu in the top right (click the 3 horizontal lines, or hamburger button).
Paste the License key into the License Key field and click enter. You should see a green bar at the top if the License key is correct.
You can confirm your expiry date in the "accounts" page, which is accessible on the same menu.