convertkit-optin-status.php

<?php

function add_optin_status($user) {
  if(isset($_POST['meprconvertkit_opt_in'])) {
    update_user_meta($user->ID, 'mepr_convertkit_optin_status', true);
  } else {
    update_user_meta($user->ID, 'mepr_convertkit_optin_status', false);
  }
}
add_action('mepr-signup-user-loaded', 'add_optin_status', 11);

function render_optin_status_field($user) {
  ?>
  <tr>
    <th>
      <label>Opt-In Status</label>
    </th>
    <td>
      <?php if(get_user_meta($user->ID, 'mepr_convertkit_optin_status', true)): ?>
        User has opted in to newsletter.
      <?php else: ?>
        User has NOT opted in to newsletter.
      <?php endif; ?>
    </td>
  </tr>
  <?php
}

add_action('mepr_extra_profile_fields', 'render_optin_status_field');