Feedback Using ads to lock up features in a paid game

I have a quiz game@ Apple Appstore with approx. +45K purchased copies.

I have now rewritten the game in Unity and added quite a few extra features. I know it is not a good idea to leverage Ads in a paid game but I was thinking of using it to unlock two of the new "big" features.

I know I should probably not use ads in a paid game but what is your thoughts about this topic? Is it worth while given is a one-off ad?

I also have new users that can be pis... of given they paid for the game I guess.

Also, is it worth it giving the money it will, or not will, generate given the relatively low #users?