[@MscTch]
 I got this same error.  It means that you have another version of the software installed.  In my situation, I bought Photomizer Pro 2 a couple of years ago, and also bought the plugin version.  Now my Pro 2 version says that the demo has expired.  While I could just uninstall it, and then install this one, my concern is that it might also uninstall the plugin, which still works.