You’re moving into a place with security components
A new home may come with an existing security system. All the alarms and cameras work, are installed in the correct places, and are ready to go. In this instance, just get the phone to call and set up a new monitoring contract. A Vivint professional will still come out to make sure there are no integration issues, and they might offer suggestions on an upgrade or two. It's a fast appointment, and you can get your monitoring set up without having a bill for any new components -- unless you add on.
The previous owners can give an existing Vivint contract to you for a one-time transfer cost to make your life easier. If the previous owners are moving to an apartment complex or smaller home, you keeping the Vivint service may be a part of the sale.
You want to move and take your home security components with you
You may want to take your favorite Vivint system with you to your new home when you move. Luckily, it's fairly easy to accomplish, as many smart devices are portable. You can uninstall each device yourself or contact a Vivint installer to take care of everything. Then a pro will set up the same features -- and any smart items you want to add -- in the new place. The home security contract will stay the same.