adhere
/ad-ˈhir/
verb
to hold fast or stick by or as if by gluing, suction, grasping, or fusing
to give support or maintain loyalty
to bind oneself to observance
The stamp failed to adhere to the envelope.
phrasal verb
to act in the way that is required by (something, such as a rule, belief, or promise)
They will adhere to the terms of the contract.