exacting

(verb): To demand and enforce the payment or performance of, sometimes in a forcible or imperious way.
(verb): To make desirable or necessary.
(verb): To inflict; to forcibly obtain or produce.
(adjective): Making excessive demands; difficult to satisfy.
(adjective): (of an action, task, etc) Requiring precise accuracy, great care, effort, or attention.
(adjective): (of a person or organization) Characterized by exaction.