Avoid searching for or using “free license keys” for Onecast or similar commercial software — the legal and security downsides outweigh any short-term gain. Choose a supported alternative (Steam Link, Moonlight, Parsec) or purchase a license to keep your Mac and data safe.
The most critical aspect of seeking free license keys for macOS is the security risk involved. While macOS is generally considered secure, the practice of downloading "key generators" (keygens) or pre-cracked versions of software opens significant vectors for infection. Onecast License Key Free Mac