You can apply the license using a graphical interface (desk-side) or via the command line for mass deployments.
No. VNC Viewer does not require a license key, though you must still abide by the terms and conditions. Only VNC Server requires licensing . realvnc offline license key new
This is the easiest method for single machines where you have physical or remote desktop access. You can apply the license using a graphical
Offline licenses are valid for (the subscription term). At renewal, you must apply an updated offline license to all servers . realvnc offline license key new