Yes, you can use any of our extensions on any domains you want. The only time we may require an additional extension subscription is if you consistently request a large amount of support for each different domain. In over a year of subscriptions to JFBConnect, we've never asked a user to obtain a 2nd subscription, but want to call it out.
For more about our subscription policies, please see:
www.sourcecoast.com/extensions/subscription-faq
Hope that helps, and thanks for your interest!