AutoCAD now operates on a subscription model (around $1,775/year as of 2025). A portable version from 2016 represents a one-time "cost" (illegal, but attractive to some).
Freelancers who move between an office PC, a home laptop, and a library workstation love the idea of carrying their workspace with them.
A "Portable" application is a version of software modified to run from a single folder (often on a USB drive) without needing to be installed into the Windows System Registry.