Although the software appears to be available for downloading, I couldn't find a way to reach the official website to obtain an answer about the status of the software or its premium service. Because of this, I also believe that Watch Tower is a discontinued application and the fact that it's not working as it should is directly influenced by the lack of a website.
I downloaded the software but it asks for a license key, which I do not have because it's impossible to acquire on.
Check your firewall, your license key (if you have one) or reinstall the application.
