Searching for is a sign of a valid need: flexibility, low resource usage, and avoiding per-machine installations. However, the software you actually find is a trap.
If you have a legitimate legacy license for AutoCAD 2015, the software introduced several major updates over previous versions: Introducing AutoCAD 2015: Overview | AutoCAD Autocad 2015 Portable
Any version labeled as "AutoCAD 2015 Portable" is an unofficial, third-party modification. Using such software carries significant risks and limitations. ⚠️ Risks of Unofficial Portable Versions Searching for is a sign of a valid
For users targeting this specific version, the Autodesk AutoCAD 2015 release introduced several major visual and functional overhauls: low resource usage
typically refers to a lightweight, portable version of Autodesk AutoCAD 2015 that runs without a full install. People seek a portable build to use AutoCAD on machines where they cannot perform a standard installation or to carry the app on removable media.