The node-locked license is based on the old school request code -> serial code license model.
It does not come with the time limit unless it is a student license, which is of 1000 days limit.
It is bound to a machine and a specific OS type, which means you cannot use a single node-locked license on both two machines, or multiple OS types, like Windows, MacOSX and Linux.
On the same machine, you can use one single license on the same OS type like Windows 7, 8, 10, or different Linux distribution, since they are of the same OS type. You might need to send me a new request code for a new registration code as the different OS versions will have different request codes.
You can use one single license on all the Maya versions in the OS, they will simply work out of the box.
The request code is gathered from ids of CPU, disk, and OS, whenever you reinstall the OS, upgrade hardware, or the adoption of the new machine as the old machine is written off, you need to send me a new request code for the new registration code. It is free.
Animators tend to switch from one studio to another, also the studio will switch your machine sometimes. As long as you are sure you are not using the license on the old machine, feel free to send me a new request code for the new registration code. It is free.