RealVNC itself offers a free tier for personal or home use. You can create an account on their website and start a 14-day trial of their full features, after which you can continue with a limited but fully functional free license. This is a 100% legal way to use the official software.
UltraVNC is built specifically for Windows operating systems, offering deep integration with the Windows environment. vnc server license key github hot
Understanding VNC Server Licenses, GitHub Repositories, and Security Risks RealVNC itself offers a free tier for personal or home use