Delete the old version of that plugin from your plugin folder, download it again from
your
account, install it and try to activate again.
The plugin folders are:
macOS VST3: /Library/Audio/Plug-Ins/VST3
macOS AU: /Library/Audio/Plug-Ins/Components
macOS AAX: /Library/Application Support/Avid/Audio/Plug-Ins
Windows VST3: C:\Program Files\Common Files\VST3
Windows AAX: C:\Program Files\Common Files\Avid\Audio\Plug-Ins