The Pro version has more functionality such as White List, Email List and allow you to custom verification message and also can "Keep silence".
Go to your WordPress Dashboard --> Plugins --> Add New and then click "Upload plugin" button on the screen.
Chose the package ( zip ) file and click "Install now" on the screen. Also remember to click "Activate plugin" after the package uploaded succesfully.
Enter your license and activate it.
Purchase Contact Form 7 Blacklist