In economics, the maximum quantity of a good legally allowed to be sold or imported is called a quota.
A quota is a quantitative restriction rather than a price restriction. An import quota, for example, limits how much of a product may enter a country during a specified period. By restricting supply, a binding quota can raise the domestic price and reduce the quantity available to consumers compared with unrestricted trade.
The right to import or sell the limited quantity may create quota rents: extra returns arising from the difference between the controlled domestic price and the relevant outside price. Who receives those rents depends on the licensing system, such as government allocation or auction.
A quota differs from a tariff, which is a tax on imports. Both can protect domestic producers, but a tariff directly generates government revenue while a quota fixes a quantity and may leave rents with license holders. A quota is binding only when the unrestricted market would exceed its limit.