You moved into a house with a pre-installed security system
Sometimes when you purchase a house, a security system is already established. All the devices work, are placed in the best places, and are ready to go. In this instance, you might find that you have to call and establish a new contract. A Vivint expert will still come to your home to ensure there are no usability problems, and they may offer ideas on upgrades. It's a quick visit, and you can have your alarm monitoring set up without having a bill for any new devices -- unless you make additions.
The previous homeowners can transfer an existing Vivint contract to you for a nominal set-up fee to make the transfer a snap. If the outgoing residents are downsizing to a condo or retirement community, turning over the security contract might be an addendum of the sale.
You are looking to move and bring your existing equipment with you
You might want to bring your existing Vivint system with you to your new house when you move. Luckily, it's fairly easy to do, as modern components are plug and play. You can take down each alarm or camera yourself or contact a professional expert to dismantle the system. Then an expert will put in the same features -- and any additions you want to make -- in the new place. Your home security contract will stay the same.