At Her Majesty's pleasure

At Her Majesty's pleasure (sometimes abbreviated to Queen's pleasure or, when appropriate, at His Majesty's pleasure or King's pleasure) is a legal term of art referring to the indeterminate length of service of certain appointed officials or the indeterminate sentences of some prisoners. It is based on the concept that all legitimate authority for government comes from the Crown. Originating in the United Kingdom, it is now used throughout the Commonwealth realms. In realms where the monarch is represented by a governor-general, governor or administrator, the phrase may be modified to be at the Governor's pleasure, since the governor-general, governor, lieutenant governor or administrator is the Queen's personal representative in the country, state or province.

People appointed by the sovereign to serve the Crown and who have no set limit to the time they occupy their given office—for example, governors general and ministers of the Crown—are said to serve at Her Majesty's pleasure. In Canada, provincial lieutenant governors are appointed by the Canadian monarch's federal representative, the governor general, and are thus described in the Constitution Act, 1867, as holding office "during the pleasure of the Governor General." Similarly, Australian ministers of the Crown are, by the Commonwealth of Australia Constitution Act 1900, appointed to serve "during the pleasure of the Governor-General."

...
Wikipedia