Detecting an instance of a prog

Hi all,
I know this might sound far-fetched bu is it possible to detect wether an online computer is running a copy of my program?

I think that you can do that by using a winsock component.
Insert the code to send a request to probably your server
that records the computers that trying to access it.

... good luck

How about if i dont have a server to handle the requests?

You can use a shared database to store the information