Hi,
The plugin is not limited by registration or purchase code, that seems to be a javascript related issue there. I suggest checking the error console in the browser, there must be a 3rd party script causing a fatal error, that is preventing the plugin from loading properly.
Localhost is not an issue either, we are developing the plugin on local test servers. Usually I suggest turning off all other plugins except the search, and switching the theme as well. That way you might be able to pinpoint, which might be causing the conflict.