VAG-COM-FAQ-3.9
From Ross-Tech Wiki
3.9 Why has VAG-COM become De-Activated on its own?
All of our Current Interfaces have Activation built-in, so VAG-COM should always be Fully Activated once it has been tested on a car. If you have a Current Interface and VAG-COM has become De-Activated, please contact us.
If you have a "dumb" interface that does not have built-in Activation, see this page: 5.3 Why has VAG-COM become De-Activated on its own?