While the era of the freely available RealVNC offline license key has transitioned into a cloud-managed subscription ecosystem, offline functionality remains alive for high-security enterprise environments. If your network must remain disconnected from the web, reaching out to RealVNC for an official Enterprise Offline Deployment package is the only secure, legally compliant path forward.
Typically, RealVNC Viewer does not require a license. However, if you are using a per-user subscription model that requires licensing on the viewer side, you can apply an offline license to the using the same License Wizard method (File -> Apply offline license). Troubleshooting Offline Activation realvnc offline license key