There is an IP address field in the license file (encoded) but usually contains "*.*.*.*"
Also I believe the IP address is not checked by SD application server. It wouldn't make sense - you can have as many application servers running in load balancing setup as you want. Which IP to check then?
Whew! I didn't think so, but the guy who used to maintain the system (over 4 years ago) put the fear in our minds. I forgot to mention that we're running 4.5, so we should be all set. I will check the rep_servers table as suggested, though.