You can force Understands licensing system into Offline mode even when you have an active internet connection. This can be useful if you have intermittent connection issues or plan on traveling for a while. Note that this will stop you from using this license on a different machine until you move back to Online Mode.
Simply select Help > Licensing > Options > Enter Offline Mode
To return from Offline Mode follow the same steps and select Enter Online Mode
If you no longer have internet access, follow the Offline Checkout instructions.