You’re buying a home with security components
A new home may come with an existing security system. All the devices function well, are hung in the best places, and are ready to go. In this example, just get the phone to call and establish a new monitoring contract. A Vivint expert will still come to your home to ensure there are no integration issues, and they might offer suggestions on an upgrade or two. It's a preliminary visit, and you can get your monitoring set up without paying for any new components -- unless you make additions.
The previous owners can give an existing Vivint contract to your family for a nominal transfer fee to make your life a snap. If the previous owners downsize to a condo or retirement community, you keeping the security contract might be a condition of the sale.
You need to move and bring your home security equipment with you
You may need to take your old Vivint system with you to your new place when you move. It should be pretty easy to transfer, as modern alarms and smart devices are portable. You can uninstall each alarm or camera by yourself or contact a Vivint installer to come and take down your devices. Then an expert will set up the same devices -- and any smart devices you want to add -- in the new place. And your home security contract will keep the same.