pmpro-member-edit-orders-add-gateway-column.php

<?php
/**
 * Add a gateway column to the member edit orders page.
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function gateway_pmpromh_orders_extra_cols_header() {
	echo '<th>' . esc_html__( 'Gateway', 'paid-memberships-pro' ) . '</th>';
}
add_action( 'pmpromh_orders_extra_cols_header', 'gateway_pmpromh_orders_extra_cols_header' );

function gateway_pmpromh_orders_extra_cols_body( $order ) {
	$gateway = $order->gateway;
	// get gateway, if gateway environment is sandbox append (test) to the gateway name.
	if ( 'free' !== $gateway && $order->gateway_environment === 'sandbox' ) {
		$gateway = $order->gateway . ' (test)';
	}
	echo '<td> ' . esc_html( $gateway ) . ' </td>';
}
add_action( 'pmpromh_orders_extra_cols_body', 'gateway_pmpromh_orders_extra_cols_body' );