leaky-paywall-hubspot-additional-data.php

<?php

add_filter('leaky_paywall_hubspot_create_contact_data', 'zeen_add_more_data_to_hubspot', 10, 2);

function zeen_add_more_data_to_hubspot( $data, $subscriber_data ) {
   
  // get the subscriber's level id
  $level_id = absint($subscriber_data['level_id']);
  
  // Append the level id to the level_id custom property
  // Notice that the level_id array key is the Hubspot internal name of the property.
  $data['properties']['level_id'] = $level_id;
  
  return $data;
  
}