UPDATE 2023-August-28
[ version 1 & 2 ] license.key needs to be located in:
[ WINDOWS ] \”login username”\Documents\Mystery Islands Music\”plug-in name”\
[ macOS ] /Library/Audio/Presets/Mystery Islands Music/”plug-in name”/
…in order to register. Reload your project or plug-in instance in order to validate.
[ version 3 ]
Since version 3, license.key must be renamed to “(plugin name).license” and placed in: Users/(your username)/Music/AURA Plugins/(plugin name)/ folder.
To make this easy, click on “register” text in the top left corner to open the file browser dialog and open the license.key file with it. Rest will be automated.