Sometimes having constant internet access just isn't possible and Chaos has plenty of articles regarding borrowing these licences for offline use, but what if you want to manage and move these licences?
The first method is to have the offline machine with V-Ray (or any chaos product) stay offline and have a machine that has the licence server installed generate an activation file (while connected to the internet) and then transfer that file across to the offline machine using a flash drive or similar. To then deactivate, have either the licence server machine connect back to the internet and release the licence or have the machine with the active licence deactivate the licence themselves from the licence server from that machine. Then just repeat the first few steps to then create another file and move it across.
The alternate method is to have the licences be reassigned from either the organisation tab or similar and once the user has their licence they then
borrow it while online and switch off from the internet for the 14 day period. While this is much simpler, both have their use cases.