Depending on which packages you are have initlally sign up, the checks upgrade differ. In order to upgrade for more sensors, look for the "Upgrade / Downgrade Options" in your services subscriptions as below at your client area.
For Flexi packages, the upgrade can be done by per sensor which cost $0.99/mo.
For Bundle packages, each upgrade will be by 5 sensors pack, with the cost of $3.95/mo per pack ($0.79 per sensor).
