Autodesk offers free access to its software for students, teachers, and educational institutions. If you're in education, this could be a viable option.
The portable version of the software also allows users to use the software on multiple computers without having to install it on each machine.
Downloading and using "portable" or cracked versions of Autodesk Revit 2015, particularly those bundled with X-Force keygens, presents significant security, legal, and operational risks. Software from unauthorized sources is a primary vector for malware, including trojans, ransomware, and credential stealers.