Can my software send information to my site and read information off my site?
Imagine that someone opens a copy of my software. The IP address of that device send to my site. So I can see if that person is a friend or not. If that person is not a friend, I will set a variable to false. The software will then read it as false then the software will close out.
Is this possible to do? If so, how can I do this?
You need to add a web service on your site then you can call the service and get an answer. You can also create a simple web page that see a white page with the result true or false. Consider using a WCF service so that it can expand if you needed more in the future.