If you still require a license for VNC 5.x, you can try the following official methods:
: If the software is already installed on a machine, you may be able to find the key in the Windows Registry at: HKEY_LOCAL_MACHINE\SOFTWARE\RealVNC\vncserver (64-bit: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\RealVNC\ ). vnc 5.0.5 license key
Searching for a reveals that this specific version of RealVNC (VNC 5.x) reached its End of Life (EOL) on October 3, 2022 . If you still require a license for VNC 5
(a legacy version of RealVNC), license keys are no longer issued or supported through traditional means as the software has transitioned to the RealVNC Connect subscription model Where to Find Your Existing License Key Transition to VNC Connect
Using version 5.0.5 is no longer recommended because it does not receive security patches, leaving systems vulnerable to modern threats. Transition to VNC Connect