PhotoLeap has a Free Trial offer on their website. Some apps will prefer you to sign up for a subscription to avoid Apple's payment processing. When this is done, you need to cancel the trial on the website where you signed up since they are billing you directly and Apple is not involved in cancelling the subscription. If you do not see the subscription when using this link, then that is the case.
If you want to cancel a subscription from Apple - Apple Support
Go to the PhotoLeap website and use the button to Manage Your Account. If you have the option to cancel there, then they are billing you directly and bypassing Apple.
https://www.photoleapapp.com
To request a refund for a purchase made using an in-app Purchase, you can use the link below. When made on the website, you will have to deal with PhotoLeap directly and if they refuse, then your only option is to dispute the charge with the bank of your payment method.
Request a refund for apps or content that you bought from Apple - Apple Support
It is not unusual for an app to also have subscription offers available on their website to avoid cancelling the subscription using the normal methods provided by Apple when it is done with an in-app purchase. Netflix and YouTube are two other examples of apps that also use this method to manage your subscription on their website.