There are several ways to obtain a serial number and product key for AutoCAD 2021:
Q: What happens if I lose my serial number and product key? A: If you lose your serial number and product key, you can contact Autodesk support for assistance.
Once you have obtained your serial number and product key, you will need to enter them during the installation process. Here are the steps:
Consider Autodesk's subscription model, which provides access to the latest versions of software, including AutoCAD, and includes support and updates.
If your deployment configuration explicitly requires a serial number entry, retrieve it legally through these channels: Check your Autodesk serial number & product key - Cadac