Returns the process identifier of the calling process
#include <WinAPIProc.au3>
_WinAPI_GetCurrentProcessID ( )
_WinAPI_GetCurrentProcess, _WinAPI_GetWindowThreadProcessId
Search GetCurrentProcessId in MSDN Library.
#include <MsgBoxConstants.au3>
#include <WinAPIProc.au3>
MsgBox($MB_SYSTEMMODAL, "ID", "Get Current Process: " & _WinAPI_GetCurrentProcessID())