A store that has approval to sell a specific brand of goods is a dealership. If you have your heart set on buying a brand new Harley Davidson motorcycle, you might want to visit a dealership for a test ride.
A business is considered a dealership if its owner is authorized to sell a certain item (in other words, they're a dealer of that product). It's most common to talk about car dealerships, whether the cars they sell are new or used, but there are also boat dealerships and recreational vehicle dealerships. This word dates from about 1916, when it was defined as "the business of an authorized trader."