If you are returned to the Welcome to the Omnisphere Authorization System page or the demo mode version of Omnisphere after reopening Omnisphere, then that means the plug-in did not accept the response code and it may have been incorrectly entered. You can check your response code by referring to the email that was sent to you after you registered. Try authorizing again with the instructions given in the Authorizing section. Make sure you are entering the response code given by the website and NOT the serial number from your user guide.
While in Demo Mode, if you accidentally press the Authorize button, simply close the interface window and reopen it.
NOTE: If you need further assistance, please contact technical support at firstname.lastname@example.org