My RAM Always using 1.5 GB, Why?

64bit System uses 2GB of RAM minimum as the requirements says. I see it as a normal.

actually.. i think its normal.. idk how to explain it.. but what i know is.. the more ram you have ,windows will eat some of it.. more and more.. yours was taken 1,5 gb (6gb ram total)
in this case mine was taken 1,9 gb (8gb ram total)

its just system thing.. idk how to explain it.. im not an expert about this.. but thats what i know..