If you need to reset the license, use the keyboard shortcut Ctrl+Alt+Shift+A (Windows) or Shift+A (Mac) while the plugin window is active to "De-Authorize" it before attempting a fresh activation.

Open Purity either in standalone mode or within your DAW (like FL Studio or Ableton Live).

In Windows, right-click your DAW (e.g., FL Studio) and select "Run as administrator" before entering the keys to ensure the license file can be written to the system.