A "portable" version of a software application is a modified version that does not require installation. In the legitimate software world (like the PortableApps platform), developers create portable versions so users can run programs from USB sticks without writing data to the Windows registry. This is common for lightweight tools like text editors or media players.
: Unofficial versions are frequently used to distribute Trojans or Ransomware . Adobe Premiere Pro Cs5 Portable 18