Who might still have a key
Previous owners, family members, dog walkers, cleaners, contractors, and lockbox codes can all leave copies in circulation. A lock change removes that uncertainty.
Rekey or full lock change
If the existing locks are solid and operate smoothly, rekeying is the most economical option. Choose a full lock change when hardware is loose, corroded, or a lower grade than you want on an exterior door.
Do every exterior opening
Include the front door, side and back doors, garage entry door, and any patio or basement door. Ask to have them keyed alike so one key opens every lock.
Consider a deadbolt or smart lock upgrade
Moving day is a good time to add a Grade 1 or Grade 2 deadbolt, or a keypad lock so you can manage codes instead of copying keys.