On Windows:
Right click on the TaskBar (Windows 7/ Windows 8) & CTRL+ALT+DEL on Windows XP, click Start Task Mananger. A windows will popup, go to Performance tab and click on Resource Moniter button. A new windows will pop up. Find your process there in the list of Memory section.
On Linux:
Get pid of the process and type top -p PID. It will display information about the process, including percent of system memory used.
