You’re buying a home with security devices
A new house may come with an existing home security system. All the alarms and cameras function well, are installed in the best spaces, and are ready to go. In this example, just turn on the phone to call and start a new service contract. A Vivint installer will still come to your home to make sure there are no compatibility problems, and they may offer suggestions on where you should replace bad outdated components. It's a fast appointment, and you can have your 24/7 monitoring set up without paying for any new alarms and cameras -- unless you get some new devices.
The previous owners can give an existing Vivint contract to you for a nominal set-up cost to make your life easier. If the previous owners are moving to an apartment complex or smaller home, turning over the security contract might be a condition of the sale.
You need to move and take your old components with you
You may want to bring along your existing smart devices with you to your new home when you move. It should be pretty simple to do, as many alarms and smart devices are plug and play. You can uninstall each alarm or camera by yourself or contact a Vivint expert to come and take care of the system. Then a pro will put in the same components -- and any smart devices you need to add -- in your new home. Your home security contract will remain the same.