In 4.4.x you should alter "include/register.php" script, find and replace this code:
PHP Code:
foreach ($common_profile_fields as $field) {
$profile_values[$field] = isset(${$field}) ? ${$field} : '';
}
// Store new password
with this:
PHP Code:
foreach ($common_profile_fields as $field) {
$profile_values[$field] = isset(${$field}) ? ${$field} : '';
}
$profile_values['membershipid'] = ${'pending_membershipid'};
// Store new password