If you only have the one key for your car i would obviously recommend getting a spare made now as its cheaper than if you have no keys. If you can’t afford a spare now, consider keeping the cost of a new key down should you loose the key you have by requesting the “car pass” for your car from a main dealer. They may charge you a small fee but sometimes will give you this for free. It will have the key code and immobiliser code on it. If you loose your car keys and you have these codes it could save you a fair bit of money when it comes to producing a new key and programming the key to your car. If you have a VW, Audi, Seat or Skoda your out of luck as they don’t issue this information. So get a spare now!!!