Can I change domain name later?

OK - yesterday I made purchase and bought Xenforo. But first thing what I needed to fill before downloading was domain name. I am in point where we change focus and looking because new domain name - same time we have ssite right now also and I would like to set up forum first there as translation and configuration anyway takes times. So my question is how important is that domain name part - just I really don't want buy new licence if I change name but forum and users remain same.