After lock cylinder replacement, do I need to program new keys or just replace the microchip from the old keys to new keys?

My car key will not turn inside the key slot. When I insert the key, the immobilizer recognizes the key, but the ignition lock cylinder has some glitches to it that makes my key not turntable. So, I am planning to replace the ignition lock cylinder. The new ignition lock cylinder comes with two keys. If after replacing the cylinder, I can mechanically turn with the new keys, but I won’t be able to start the car because the immobilizer doesn’t recognize the new key. In that case, do I need to program my new key to match with the immobilizer? Or I can avoid this hassle by just carrying my old key around because it has the microchip that communicates with the immobilizer.