Disable purchase for non-logged-in users

// Disable purchase for non-logged-in users.
function m3wc_woocommerce_is_purchasable( $is_purchasable, $product ) {
    if ( ! is_user_logged_in() ) {
        return false;
    }

    return $is_purchasable;
}
add_filter( 'woocommerce_is_purchasable', 'm3wc_woocommerce_is_purchasable', 10, 2 );