The Version GUID is hardcoded in your app and it allows you to use the functions.
The product key is what you send to customers so they can activated your app.
Best articles to view:
https://wyday.com/limelm/help/getting-started/
https://wyday.com/limelm/help/using-turboactivate-with-csharp/
They walk you through how to use TurboActivate.