In feudalism a knight must

The dominant social system in medieval Europe, in which the nobility held lands from the Crown in exchange for military service, and vassals were in turn tenants of the nobles, while the peasants (villains or serfs) were obliged to live on their lord's land and give him homage, labor, and a share of the produce, notionally in exchange for military protect

In feudalism Knights had to perform military services for the king in exchange for a portion of land