This system was robust for its time but not unbreakable.
But the hidden costs were real:
You may need to generate a "request code" from the software's activation wizard to receive an official activation code from Autodesk Support .
If you must maintain access to 2005-era files or workflows, consider these safer methods:
For a student or freelancer in 2005, AutoCAD 2005 cost ~$3,750 (≈$6,000 today). A keygen was free. That economic pressure drove the search for a “better” crack.