Tap “Premium Service” in the app's “Settings” screen and purchase Premium. Your purchase unlocks all of the following benefits:
・No more ads
・Unlimited access to all colours
・Unlimited group creation & duplication
・Unlimited access to all sound effects
・Change the app icon
・Unlimited counters
You can choose from three purchase options: “Monthly”, “Annual”, and “Lifetime”. See the next question for the differences.