iSpring Suite deeply integrates with Microsoft PowerPoint via COM add-ins and writes to the Windows Registry, Program Files, and AppData folders. A true "portable" version (one that runs from a USB drive without installation) is technically extremely difficult to create and maintain.
While torrents might seem like a convenient option, there are legitimate ways to access iSpring Suite:
The legitimate software costs around $770 for a perpetual license (as of recent pricing). That's why many people hunt for a "free" version.