I wonder if the developer did anything to ask users to buy the legitimate version. I have an app in the App Store and I limit users to a certain number of photo

I wonder if the developer did anything to ask users to buy the legitimate version. I have an app in the App Store and I limit users to a certain number of photo uploads before giving them a notification to buy it. I've had about a 20% piracy rate. 0.85% of the total (4% of pirates) bought the app after pirating and 0.63% bought it before seeing the message.