Amazon

Amazon Key faced a bumpy start in late 2017, with plenty of folks mocking the program's concept of delivering packages inside people's homes.

But, a year and a half later and following a slight name change (it's now called Key by Amazon), the service is still kicking and even undergoing its first geographic expansion since launch.

Starting Tuesday, Amazon Prime customers in these 13 additional cities will be able to use Key: Charlotte, North Carolina; Columbus, Ohio; Fresno, California; Grand Rapids, Michigan; Hartford, Connecticut; Las Vegas; Norfolk, Virginia; Oklahoma City; Omaha, Nebraska; Rochester, New York; Stockton, California; Virginia Beach, Virginia; and Wilmington, Delaware.

Key is now available in 50 US cities, and the expansion includes all three parts of Key's service -- in-home, in-car and in-garage deliveries. You can check if it's in your area here.

Also on Tuesday, Amazon launched its Key in-garage delivery service using Chamberlain's myQ-connected garage-door software.

Now playing: Watch this: Here's how Amazon Key In-Car delivery works

Amazon wants to use Key to create a new platform for its services, giving customers more secure deliveries and digital access to their homes. It eventually plans to add Amazon Home Services to the program, letting people use Key for home cleaners, dog walkers and repairmen. If successful, Key could give Amazon an advantage against its retail rivals in home deliveries, product installations and other services.

Key is also part of Amazon's bigger effort to build up its presence in people's connected homes, with the company selling Echo smart speakers, Fire TV media streamers and Ring video doorbells.

Key in-home shipping works by letting a delivery person unlock a customer's internet-connected door lock and place a package just inside the door. The customer can watch the delivery happening using an Amazon Cloud Cam security camera. Key should help Amazon cut down on package thefts and rain-soaked boxes left on people's porches.

Prime customers, who pay $119 annually, can use Key after installing the needed hardware, such as an internet-connected door lock and security camera for in-home delivery. In-car delivery is available for only certain types of cars and requires an active OnStar or Volvo On Call account.

The e-commerce giant has avoided offering specific data on how big Key is or how often people use it, but has previously pointed to its positive ratings on Amazon and said Prime customers have used the service a lot.