Beurre Laitier is a French term used to describe butter made in a creamery or small dairy, as opposed to on a farm or in a factory; so it’s half-way between artisanal and industrial. In effect, it’s the English expression “creamery butter”, though it has probably been many decades since anyone in English knew what that meant.
The butter will be 80% butterfat if salted; 82% butterfat if unsalted.
It can be made from pasteurised or raw milk.
The creameries are inspected frequently by a department of the French Ministry of Agriculture.
At 35 F (2 C) the butter can be stored about 20 days, but now with more sterilization happening, this butter can actually last up to 3 months if refrigerated.