late 14c., "formal authorization, official permission, permit, privilege," from Old French licence "freedom, liberty, power, possibility; permission," (12c.), from Latin licentia "freedom, liberty; unrestrained liberty, wantonness, presumption," from licentem (nominative licens ), present participle of licere "to be allowed, be lawful," from PIE root *leik- "to offer, bargain, make a bid" (possibly source also of Lettish likstu "I come to terms").

Meaning "formal (usually written) permission from authority to do something" (marry, hunt, drive, etc.) is first attested early 15c. Meaning "excessive liberty, disregard of propriety" in English is from mid-15c. In Middle English spelled licence , licens , lisence , lissens , licance . There have been attempts to confine license to verbal use and licence to noun use (compare advise / advice , devise / device , and see note in OED); in the U.S., license tends to serve as both verb and noun.

Poetic licence "intentional deviation from recognized form or rule" is from 1733, earlier as lycence poetycall (1530). The licence-plate is from 1870 (of dogs and wagons before automobiles); licence-number is by 1903.

late 14c., plesire , "source of enjoyment, pleasing quality or thing, that which pleases or gratifies the senses or the mind," from Old French plesir , also plaisir "enjoyment, delight, desire, will" (12c.), from noun use of infinitive plaisir (v.) "to please," from Latin placere "to please, give pleasure, be approved" (see please (v.)).

Also from late 14c. as "discretion, will, desire, preference," as in at (one's) pleasure "when one wishes." From mid-15c. as "gratification; feeling of enjoyment, liking." The meaning "sensual gratification" is from early 15c. That of "indulgence of the appetites as the chief object of life" is attested from 1520s. The ending was altered in Middle English by influence of words in -ure ( measure , etc.).