The keys you buy at chain stores are not programmed keys. They are clones of the key you have. The problem with them is that they have a battery in them. When the battery dies, your key stops working and you are screwed.
Either program a new one with Forscan or find a real locksmith and pay the $100 for a real one.
The real keys have nothing but a small coil in them. The car actually is programmed to recognize the key. That's why a locksmith has to plug a computer into the car to program it for the new real key, and why Walmart only needs your key to make a cloned copy with a battery in it which mimics your original.