What have you tried so far?
The procedure is fairly simple.
Login here at unity. Go to your account, click on Licenses and find your license and click reset under the domain to reset the license so it can be used for another domain.
Then go into admin on your dolphin site and to advanced settings, variables and remove any license code there, save and logout.
Now to put the license back in so it will register, you must log back into your site from the back door. Logging in from the front end and entering the license in admin will not register it. So it must be done from the back administration entrance.
http://www.yourdomain.com/administration/
Log in and it will prompt for you license. Enter it there, and you should be good to go.