Is Rhino 3D a one-time purchase?

I'm curious to know, is Rhino 3D a software that requires a one-time purchase, or does it come with recurring fees? I'm evaluating my options for 3D modeling software and would like to ensure I'm making the most cost-effective decision. Does purchasing Rhino 3D grant me perpetual access to updates and new features, or is there a subscription model in place? Understanding these details is crucial for me to determine if Rhino 3D aligns with my financial planning and software requirements.