These notes are for the 4.03 version of the app from http://www.mockupscreens.com
Used Wise Package Studio SetupCapture and took a "before" snapshot.
Ran the vendor's installer.
Had it launch the app and entered the registration key.
Removed the desktop icon the installer created.
Moved the shortcuts it created in my profile to the All Users profile.
Deleted the "uninstall" shortcut the installer created.
Deleted the changed files detected anywhere other than the C:\Program Files directory.
Deleted the Registry keys found except for those under HKEY_CURRENT_USER\Software\MockupScreens and \MockupScreens4.
and the automatically created HKLM\Software\Microsoft\Uninstall key.
The result was a package that installed and did not prompt for registration information, but seems to work otherwise.