Im using PhpED commercial version 19.5, OS 64bit 16GB Ram but still having warning "System is running low on virtual memory", I cannot close this window and can not do anything even can not close IDE I must use task manager to close it, and worst is I did not even created a single project there are no huge files or cache etc.

I believe there is something else eating up your memory.
Check out memory usage by size in Task manager -> Details - > sort by column Memory.
This has most likely nothing to do directly with PhpEd, message from PhpEd is a consequence, not the reason.
For example when I was running elasticsearch /ES/ with large indices - PhpEd started to show warnings about low memory - but when I decreased memory granted to ES, those messages disappeared.