However, users should be aware of potential security risks associated with running Office 2013 Portable:

Office 2013 is the last version to run comfortably on 2GB RAM Windows 7/8 machines. The portable variant consumes even fewer resources because it doesn't install background services like Click-to-Run or Office Telemetry. On an old netbook, this is significantly than any modern Office suite.

Whether portable or installed, Office 2013 introduced several core improvements: End of support for Office 2013 - Microsoft Support

Stay productive, stay portable, and most of all – stay safe.