According to some data, I was able to dig up, the registration message is a glitch in the program that appears each time you run the screensaver on a newer Windows version. In theory, you would need to update the application to its latest version and thus solve the problem, but it seems that the company went out of business and their website as well as their software is no longer accessible.
This leaves us with option number two: removing the application from the Windows Startup list. Since I don't know which version of Windows you are using, I can only give you one way to get to the Startup list: press the Win and R keys together, then type msconfig in the run box and press Enter. In the new window that opens up, go to the Startup section, look for an item called Register with AzureBay's icon on it and delete it.
To stop the company from spamming your email, you can either choose to unsubscribe or block them from your email client, whichever that may be.