Whenyou first move into the property you should consider changing the locks to the property.
You never know if any copies have been made to your keys by previous occupants or whether copies have been given to friends, neighbours etc.
To give you piece of mind during in your new home, speak to a registered locksmith who will be able to find a new lock and cut your new keys.
You might also want to give a copy of your new key to someone you trust who lives nearby in case of an emergency or if you get locked out!
Look around the property and consider the security of the place. Windows, Doors, Loft Access, Garages and Outbuildings should be secured in order to protect your possessions.