If you entered the LiveID for your subscription on the additional 2 PCs when selecting Subscribe when you installed, they are part of your subscription. If there never was a subscribe link when you installed, then you should check the date a time on those PCs.
If you want to see if you added them to your subscription, make you PC a hub via the Your OneCare Circle link. You can select "stop being a hub PC" after you've seen the additional two PCs show up in the Circle on your PC, if you wish.
-steve