BUGG

Plugin still works, but there is bug, replace the function with this.

function update_views($post_id) {
    global $wpdb;
    $p2_table = $wpdb->prefix.unique_p2_table();
    $views = get_total_views($post_id) + 1;

	if (get_total_views($post_id) == 0)
        insert_views($views, $post_id);
	   $result = $wpdb->query("UPDATE $p2_table SET view = $views WHERE post_id = '$post_id' AND ip_addres = '".$_SERVER['REMOTE_ADDR']."'");
   return ($result);
}

https://wordpress.org/plugins/unique-post-view-conter/