Once your license expires you can still use the plugin, but only with the free features. Also you will no longer be able to receive updates or support for the plugin.
However, the support for free features is still available. You can create a support ticket in the WordPress forum. We are answering you ASAP based on our work load.
The data of PRO features in your database won’t be lost. We’ll keep it in case you can resume the PRO license you don’t lost your configurations. If you want to delete all the plugin data from your database there is an option to do it, in the plugin settings page.