Offer Free shipping to PMPro Members.

pmpro_free_shipping_to_members.php

<?php

/**
 * If user does not have a membership level only offer flat rate.
 * If is a Paid Memberships Pro, force free shipping!
 *
 * Add this code to your PMPro Customizations Plugin - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 *
 *
 * PLEASE NOTE: Clear WooCommerce Transients for this to take affect if not working.
 * NAVIGATE TO 'WooCommerce' > 'Status' > 'Tools' AND SELECT 'Clear Transients'.
 */


function pmpro_only_show_flat_rate_to_non_members( $rates ) {

	if( pmpro_hasMembershipLevel() ){
		foreach( $rates as $rate_id => $rate){
			if( 'flat_rate' === $rate->method_id ){
				unset( $rates[$rate_id] ); 
			}
		}
	}else{
		foreach( $rates as $rate_id => $rate){
			if( 'free_shipping' === $rate->method_id ){
				unset( $rates[$rate_id] ); 
			}
		}
	}

	return $rates;
}
add_filter( 'woocommerce_package_rates', 'pmpro_only_show_flat_rate_to_non_members', 100 );