What is the origin of the idiom "at one's pleasure" and when to use it?

The phrase "at one's pleasure" originated during medieval and early modern times in English. It means that someone has the freedom or authority to do something as they like or prefer. It is commonly used in formal situations, like legal or official documents, to give someone the power to make decisions or take actions according to their own choice. It can also be used more generally to show that someone has the freedom to do something when it suits them or when they want to.