You moved into a place with a pre-existing home security system
Sometimes when people close on a home, a modern security system is already established. All the devices work, are hung in the correct areas, and are ready to go. In this case, you might find that you have to call and set up a new contract. A Vivint installer will still come to your home to make sure there are no usability issues, and they might offer suggestions on upgrades. It's a preliminary trip, and you can have your 24/7 monitoring set up without having a bill for any new components -- unless you get some new devices.
The outgoing owners can transfer an existing Vivint contract to your family for a nominal set-up cost to make your life easier. If the previous owners downsize to a condo or smaller home, you keeping the Vivint service may be a part of the sale.
You want to move and bring your existing devices with you
You may want to bring your old smart devices with you to your new home when you move. That’s pretty simple to accomplish, as most smart devices are wireless. You can uninstall each alarm or camera by yourself or call a Vivint installer to dismantle the system. Then an expert will set up the same components -- and any additions you want to put in -- in the new place. The home security contract will remain the same.