At one's pleasure or discretion; at will.
Frequently with reference to the holding of or appointment to ecclesiastical, legal, or government office.
ad bene placitum/ˌad ˌbɛneɪ ˈplakɪtəm/ /ˌad ˌbɛni ˈplasɪtəm/
Early 17th century; earliest use found in Thomas Scott (d. 1626), protestant polemicist. From post-classical Latin ad beneplacitum at good pleasure from classical Latin ad + post-classical Latin beneplacitum good pleasure (Vetus Latina), use as noun of neuter past participle of beneplacere to please (Vetus Latina) from classical Latin benē well + placēre to please.