You moved into a house with a pre-existing home security system
Sometimes when you close on a home, a security system is already in use. All the alarms and cameras work, are hung in the right areas, and are ready to go. In this case, you might discover that you have to call and establish a new contract. A Vivint expert will still come out to make sure there are no compatibility issues, and they might offer options on upgrades. It's a fast trip, and you can have your monitoring set up without paying for any new alarms and cameras -- unless you add on.
The outgoing owners can transfer an existing Vivint contract to your family for a nominal set-up cost to make your life simpler. If the previous owners downsize to a condo or retirement community, transferring the home security contract may be an addendum of the sale.
You need to move and take your old components with you
You may need to take your old home security components with you to your new place when you move. Luckily, it's fairly simple to transfer, as most smart devices are wireless. You can uninstall each component yourself or contact a professional installer to take care of everything. Then a pro will hang the same devices -- and any additions you need to make -- in the new house. The home security contract will remain the same.