Hi,
It would depends.
If you want to do a manual save (without any check) and if you know the serial_id, you can do this:
$serialClass = hikaserial::get('class.serial');
$serial = new stdClass();
$serial->serial_id = $serial_id;
$serial->serial_status = 'used';
$serialClass->save($serial);
Otherwise, you can use the function
$serialClass->find($serial_data, $filter = null, $orders = null) if you want to find a serial. The function would return you a list of serial.
There is the function
$serialClass->consume($serial_id, $extra_data = null, $check_user = true) to use the consume feature.
The check_user if for checking find only on serial which are assign to the current logged user.
The extra_data is for storing new extra_data information to the serial.
Regards,