The Platform Assistant server (named paserver) is a command-line application that can be installed on Windows and Mac OS X. You install the Platform Assistant on a remote system, in the same network as your development system, to let RAD Studio interact with that remote system, so that you can develop cross-platform (multi-device) applications for Mac OS X, iOS, or Win64 (this last from a Win32 development system).
Excerpt taken from the Embarcadero Docs.