Once you purchase the ad-free version of the game, you'll find two Trivia Crack applications in the Store: with and without ads. This is because the two apps are independent for each other.
To avoid any misunderstanding and enjoy the ad-free version, we recommend that you remove the free version off your device.
In case you have a new device and cannot complete access to the ad-free version, we recommend you visit the article: Why am I being asked to pay if I already bought the ad-free version?