You can ask for your money back using the website provided by Apple.
1. Login with the Apple ID you used to make the in-app purchase.
2. Go to Purchases > Apps
3. Find the in-app purchase for our app and tap the right-side button "Report a Problem"
4. Fill and submit the refund form
Apple will review your request and refund your purchase.
From time to time, Apple may refuse a refund request if they find evidence of fraud, refund abuse, or other manipulative behavior that entitles Apple to a corresponding counterclaim.
Please contact Apple Support for questions regarding denied refunds, as they charge your credit card and they are the only ones who can verify or reverse transactions (not the app developers).
Also, keep in mind that when you installed Cleaner on your device you accepted the "Terms & Conditions" agreement.
Please check Chapter 3, "Usage Risks" that says "Only Apple can refund your PRO & Cloud upgrades (the developer is not responsible for possible denied refunds)."