How do you make the script work for the gamepass?

My question basically is how do you make a gamepass, You know like an "Extra Sword" Pack and then when someone buys it it shows up for them in the game. How do you do this?

Here is a wiki link for checking if someone has the pass.

PlayerHasPass Method

Since it is not a request site, I won't write the code for you. If you know some scripting, you can use the above method to make what you want.