This is taken from the Jeep Compass owners manual. This is the instructions on programming an ignition (Sentry) key.
NOTE: Only keys that have been programmed to the vehicle electronics can be used to start the vehicle. Once a Sentry key has been programmed to a vehicle, it can not be programmed to any other vehicle.
At the time of purchase, the original owner is provided with a four digit PIN number. This number is required for dealer replacement of keys. Duplication of keys may be performed at an authorized dealer or by using the Customer Key Programming procedure (below). This procedure consists of programming a blank key to the vehicle electronics. A blank key is one which has never been programmed.
NOTE: When having the Sentry key Immobilizer System serviced, bring all vehicle keys with you to the dealer.
You can program new keys to the system if you have two valid sentry keys by performing the following procedure:
Repeat this procedure to program up to a total of 8 keys. If you do not have a programmed sentry key, contact your dealer for information.