function MYMODULE_admin() {
  $form = array();
  $form['style']['business_logo_fid'] = array(
    '#title' => t('Business Logo'),
    '#type' => 'managed_file',
    '#description' => t('Upload a logo for your business in one of the following formats: jpg png jpeg.'),
    '#default_value' => variable_get('business_logo_fid', ''),
    '#upload_validators' => array(
    'file_validate_extensions' => array('jpg png jpeg'),
    ),
    '#upload_location' => 'public://',
  );

  $form = system_settings_form($form);
  $form['#submit'][] = 'after_save_ui';
  return $form;
}

function after_save_ui($form, &$form_state) {

    $business_logo_fid = variable_get('business_logo_fid');
    if ($business_logo_fid) {
        $business_logo = file_load($business_logo_fid);
        $business_logo->status = FILE_STATUS_PERMANENT;
        file_save($business_logo);
    }

}