Customise License Expiry Email Headers

The body of the Commerce License Expiry message can be customised by altering a copy of the template commerce-license-expire.html.twig in a custom theme.

Is there a simple way to customise the email subject? Is the 'subject' value themeable, or does the plugin need to be extended, overridden or modified?

The email subject is built in commerce_license/src/Plugin/AdvancedQueue/JobType/LicenseExpireNotify.php public function process():

$params = [
      'headers' => [
        'Content-Type' => 'text/html; charset=UTF-8;',
        'Content-Transfer-Encoding' => '8Bit',
      ],
      'from' => $from,
      'subject' => $this->t('Your purchase of @license-label has now expired', [
        '@license-label' => $license->label(),
      ]),
      'license' => $license,
    ];

So I would need to alter the value for $params['subject'] value