If you are a professional: The CounterSketch subscription pays for itself in one or two custom ring sales. The time you waste fighting a broken crack is more expensive than the monthly fee.
If you are a hobbyist: Skip the cracks. Use Blender. It is truly free and has a massive community of jewelry designers on YouTube (search "Blender jewelry tutorial").
If you are a student: Email Stuller support directly. They often provide extended educational licenses for free to accredited jewelry design programs.