Perimeter treatments might be part of your service contract, where you receive pest control treatments on a scheduled basis. You and your technician should discuss whether you might like a service contract to prevent pest activity, or whether you prefer to treat pests reactively (only when you see them). The type of service you choose is up to you alone.
A pest control technician treating the exterior of a house

M. Waldvogel - NCSU - Entomology & Plant Pathology