I am having the same problem on both Windows 8 and Windows 10, I also cannot get the software to register.

When I enter in my first/last name + email, and the key... I get messages:

"Error connecting to server. Please connect to the internet and/or allow Blacksmith3D through the firewall/etc. and try again."

"Please restart the program to complete the registration process."

"!Registration successful."

If I turn off Windows Firewall I can get the "Error connecting to server...." message to go away, but it doesn't matter.

Even leaving the firewall turned off permanently, registration never takes... fields are remembered when I go to "register...." menu option, but I can't ever get Save option, etc to be enabled.  

Since I can't save, I can't use program at all really.