I might be able to help here, as I just did the same thing. My understanding, and this could be wrong, is that you just have to log into the new render server with your VRay ID on your main machine. It just needs to be able to get to it's location online to find it. I think that once you start to render, the license is used up. If you try to go back and render on the laptop while a render is going, it should refuse you. What is nice however, is that once you get the new machine logged in, you should be able to render either on the laptop or your main machine as long as there is only one session, whichever you happen to be working from. Also, I often go through WiFi in different locations, and VRay still fires up and renders because of how this works. It is really nice. I have not gone back to our laptop (some else in the dept needs it to use AutoCAD) to actually test this theory, however.