It was a dead key. Probably blacklisted years ago when the software phoned home to the servers. The list was old; he hadn't updated his backup since 2019.
If you have lost your legitimate key, use these methods to retrieve it: Email Search : Look for confirmation emails from (ABBYY's official e-shops). In-App Check : If the software is already installed, go to Help > About > License Info . The serial number or Support ID will be listed there. Physical Copy abbyy finereader 15 serial number list
Here is an overview of why legitimate access is the better choice and how you can get it. Why Avoid "Serial Number Lists"? It was a dead key