Sorry to hear that you have problems. The present latest version of Login One! Premium Edition for J3 is 3.4.10.
You did not mention your Joomla! version, nor your plug-in version, but it should not matter really, because the plug-in will warn you if it is not compatible with your Joomla! install.
> Did you enable both the Login One! authentication AND user plug-ins?
> Are you able to log into the back-end as a super user? If so, you can check the above.
> If you are logged into the back-end, are there any notices/warning by the plug-in?
> If you have access to the back-end, you may empty the Joomla! cache and see if that helped.
> There is a trouble shooting guide on www.innato.nl/index.php?option=com_content&view=article&id=55