Which would you like? Or specify another legal angle.
Autodesk gives to students and educators. You can legally download the latest AutoCAD version. While not portable, you can install it on your personal laptop.
LibreCAD is completely free, open-source 2D CAD software. While less feature-rich than AutoCAD, it runs on Windows, Mac, and Linux, including older computers, and requires no license.
AutoCAD 2010 is now considered "legacy" software and is no longer supported by Autodesk. Instead of risking your computer with an unofficial portable version, consider these modern, safer alternatives: