I don't understand what URL jetpack is working on

To register jetpack, my wordpress username was not working to register at my own domain. I had to create a new account using a subdomain of wordpress like [mydomain].wordpress.com instead of mydomain.com Jetpack was installed on my domain using simplescripts at my hosting provider, but I don’t need the wordpress.com subdomain, as I already have my own domain where wordpress is installed. Now that I have successfully registered at the wordpress subdomain, does that mean jetpack will work on [mydomain].com or is it only supposed to work at [mydomain].wordpress.com which I don’t need. If so, I just wasted 1/2 hour.