V-Ray for Katana requires a V-Ray license server using either the online system or a USB dongle. V-Ray for Katana can use the same license server as other V-Ray products. To verify that you have the appropriate licenses: open a browser and visit the site http://licenseserver:port, where licenseserver is the address of your license server and port is the port (default is 30304) where the server is running at. There you should see a product button for V-Ray | Katana 3.0 and clicking it will give you the total number render and interface licenses available.
If there's an issue with the licenses displayed on this page, you should contact Chaos Group Support, to update your licenses. If you want to update your licenses on your dongle, contact Support and send them the context.wbc file.
Changing your License Server Settings/Location
If you are running the V-Ray license server on a different machine, you need to tell V-Ray for Katana where to look for it. To do this, run the setvrlservice program from the tools subdirectory in your V-Ray for Katana installation. For more details on this process, please see the Change your License Settings page.