Adds the next billing date for a recurring membership to the Members List page of Paid Memberships Pro and the CSV file generated by it.

pmpro_next_billing_date_customization.php

<?php
  /*
  * To add 'Next Billing Date' to Members List
  */
  //Add 'Next Billing Date' Column to Members List Header
  function my_pmpro_memberslist_extra_cols_header($theusers)
  {
      ?>
      <th><?php _e('Next Billing Date', 'pmpro');?></th>
      <?php
  }
  add_action('pmpro_memberslist_extra_cols_header', 'my_pmpro_memberslist_extra_cols_header');

  //Add 'Next Billing Date' Column to Members List Rows
  function my_pmpro_memberslist_extra_cols_body($theuser)
  {
  ?>
  <td>
      <?php 
          if(!empty($theuser->data->ID)){
              $nextPayment = pmpro_next_payment($theuser->data->ID, 'success', 'date_format');
              if($nextPayment == "")
                  echo "None";
              else
                  echo pmpro_next_payment($theuser->data->ID, 'success', 'date_format');
          }
      ?>
  </td>
  <?php
  }
  add_action('pmpro_memberslist_extra_cols_body', 'my_pmpro_memberslist_extra_cols_body');


  /*
  * To add 'next_billing_date' to CSV Export
  */
  //add the column to the export
  function my_pmpro_members_list_csv_extra_columns ( $columns ) {
      $columns["next_billing_date"] = "my_pmpro_add_bill_date_to_csv";
      return $columns;
  }
  add_filter( 'pmpro_members_list_csv_extra_columns', 'my_pmpro_members_list_csv_extra_columns', 10 );
  //call back to get the column a value
  function my_pmpro_add_bill_date_to_csv( $user ) {
      //this is an example to retrive user meta
      $column_value = pmpro_next_payment($user->ID, 'success', 'date_format');
      if($column_value=="")
          $column_value = "None";
      return $column_value;
  }
?>