Every Lot within Sterling Gate and any of its Sectors is part of the Sterling Gate Homeowner's Association. Membership is not optional.
Whether stated or not, at closing you accepted the deed to your property and home. At that time, by acceptance of your deed, you became a mandatory member of the Sterling Gate Homeowner's Association. All Members (Home and Lot Owners) are legally required to pay Assessments (Also referred to as Dues).
This article explains what your Dues pay for and what happens, legally, if you do not pay your Dues.