If you mean that there's a menu option in the application that allows you to add the license, then open up the app and open the dialog box that allows you to add the license.
Then run an INCTRL snapshot (
http://www.devhood.com/Tools/tool_details.aspx?tool_id=432)
Then add the license and run another snapshot. Then it will show you the reg /file differences.
You could also do this with an Installshield Repackager session.
Like I said, it doesn't always work.
Try Appdeploy first!
Cheers.