That little program is still in Beta 1 only been out briefly, only downloaded 186 times, and reviewed by 2 people. One says it takes 20-40MB of RAM to run.
Are you sure it isn't sending information out and using more unexplained allotment loss? I imagine you have tested it. Just askin...
Until Charles can respond:
Windows Task Manager shows a small amount of RAM assigned to GlassWire:
As to it "calling home" (I use Net Guard to monitor usage) Net Guard indicates there has been no upload activity on the part of GlassWire. The computer has only been turned on for about an hour at this point. If I see GlassWire doing a "data dump" later in the day I'll report back: