If you have a valid license, here is how to use your product key and serial number to generate an activation code.
The is a code that distinguishes which Autodesk product you are installing. Unlike the serial number (which is unique to you), the product key is the same for everyone installing the same version of AutoCAD 2010. It tells the installer which specific software to activate within the Autodesk family (e.g., AutoCAD vs. AutoCAD LT vs. AutoCAD Architecture). Autocad 2010 Product Key Serial Number And Activation Code