You can block the lost key using the iLOQ HOME app. You will need to update the locking system to give information about the blocked key. If you don't have any other keys yourself, you can use another key that is programmed in the same locking system, for example a neighbour's key. Use that key in your apartment lock to update the latest block list to your apartment door. There is no need to show the key to the front door; it updates automatically. But it is a good idea to use the key in other locks that you have access to which don't have iLOQ Online readers, such as storage rooms, to update the locks.