Pixinsight License File Location -

If you lose your license file, you can usually retrieve it by logging into your PixInsight user account on the official website and re-downloading it. However, keeping a local backup saves time and ensures you can get back to processing your astrophotos immediately.

/Users/JohnDoe/Library/Pleiades/pixinsight-license pixinsight license file location

~/.Pleiades/