Pasteurized butter is made in factories, and is almost always government inspected.
It’s not actually the butter that is pasteurized, but rather the milk / cream that the butter is made from.
The milk or cream can be pasteurized using HTST or UHT methods
In order to make cultured butter, bacterial starter cultures have to be re-introduced to “age” the cream.
Pasteurization extends storage life of butter up to 2 to 3 months under normal refrigeration