Where can a player find a Sims 3 product key?

The Sims 3 product key is either on a small piece of paper inside the box or on the back of the game manual inside the case. The product key is 20 characters long.

If someone loses the box or piece of paper with the code on it, they can find it under the registry key that stores the serial number for the Sims 3 on a computer. This does not mean someone has to edit the registry, but there is still a risk that this method can result in altering registry keys or deleting them, both of which can cause significant damage.