Add a custom column to the Memberships > Members admin page for a user field added via Register Helper using a WP List Table filter (PMPro v2.2+).

my_pmpro_members_list_add_company_column.php

<?php
/**
 * Add a custom column to the Memberships > Members admin page for a user field
 * added via Register Helper using a WP List Table filter (PMPro v2.2+).
 * 
 * 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/
 */
 
/**
 * Add 'Company' Column to Members List Header.
 */
function my_pmpro_members_list_add_column( $columns ) {
    $columns['company'] = 'Company';
    return $columns;
}
add_filter( 'manage_memberships_page_pmpro-memberslist_columns', 'my_pmpro_members_list_add_column' );

/**
 * Add data for member's Company to the Members List.
 */
function my_pmpro_members_list_user_company( $user ) {
	$company = get_user_meta( $user->ID, 'company', true );
	if ( ! empty( $company ) ) {
		$user->company = $company;
	} else {
		$user->company = '&#8212;';
	}
	return $user;
}
add_filter( 'pmpro_members_list_user', 'my_pmpro_members_list_user_company' );