In Windows, V-Ray License Server runs as a Windows service on the machine where it's installed and should be present at all times. Note that the Microsoft Windows 10 Creators Update may remove (delete) the service (VRLService) for the V-Ray Online License Server. As a result - the License Server will stop providing licenses to V-Ray instances and its status will not be visible - http://localhost:30304 status page will not load in the internet browser on the license server machine.
If you experience any licensing issues after applying this Windows 10 update, please re-install the V-Ray Online License Server in order to solve it. You can download it from here.