function wpf_limit_displayed_tags( $tags ) {

    foreach ( $tags as $i => $tag ) {
        if ( false == strpos( $tag, 'member' ) ) {
            unset( $tags[ $i ] );
        }
    }

    return $tags;

}

add_filter( 'wpf_get_setting_available_tags', 'wpf_limit_displayed_tags' );