Hide products from users who are not logged in using tags in WooCommerce

functions.php

function wc_exclude_by_product_tag( $query ) {
    if ( $query->is_main_query() && is_woocommerce() && !is_user_logged_in() ) {
        $taxquery = array(
            array(
                    'taxonomy' => 'product_tag',
                    'field' => 'id',
                    'terms' => array( 6 ), // the ID of the product tag
                    'operator'=> 'NOT IN' // exclude
                )
            );

        $query->set('tax_query', $taxquery);
    }
}
add_action( 'pre_get_posts', 'wc_exclude_by_product_tag' );

https://stackoverflow.com/questions/34684881/hide-products-from-users-who-are-not-logged-in-using-tags/