If you do not cancel a trial at least 24 hours in advance then it may start charging you. Once this happens you must pay for it. While you are welcome to contact Apple about this as mentioned in another reply, I have not seen anybody say that they had a charge reversed. Once you have paid you can ask for a refund but depending upon where you live that may not be granted.
Confirm you have canceled any subscription automatic renewal (if you simply delete an app this does not cancel subscriptions):
Review the information in this support article by clicking on the link to learn how to cancel a subscription from Apple. ➔ https://support.apple.com/118428
If you subscribed to this directly with a third party, see: https://support.apple.com/118126 instead. You need to work directly with the vendor, not Apple.
Notes:
• If you signed up [which involves very intentional steps by you or a user of your device, accompanied by warnings along the way] for a free or discounted trial subscription and you don't want to renew it, cancel it at least 24 hours before the trial ends." Note that by using an app like this you are automatically agreeing (always read the fine print) to this happening, are responsible for reading if this will happen, and canceling the subscription before the trial ends. E.g., https://discussions.apple.com/thread/256230049?answerId=261793271022 Exceptions apply in some countries https://support.apple.com/108098
• Deleting an app does not cancel a subscription.
• An existing subscription will normally continue until the end of its term and may then renew automatically. Stopping automatic renewal is effectively canceling it. "If you don’t see Cancel Subscription, then the subscription is already canceled and won't renew." The "Expires" date means the current subscription will just run until then. Note special conditions for some countries: https://support.apple.com/108098
• Read the article to see what to do about subscriptions that do not appear in your list. If you still can't find a subscription, contact Apple Support using the link at the end of the support article.
• Canceling a subscription does not automatically start a refund.
• If you had a free trial previously, you do not get a second one and a subscription will start immediately.
• This thread (particularly posts by MacJimID) outlines complex scenarios regarding subscriptions and trials. ➔ https://discussions.apple.com/thread/256149847
If you wish to pursue a refund, follow the directions in this support article about how to request a refund for apps or content that you bought from Apple ➔ https://support.apple.com/118223 Also review the terms in section B of https://support.apple.com/fht204084 The likelihood of you getting a refund will vary greatly from region to region. In some regions refunds are only made to remedy defective or unavailable product. You can request a refund on other grounds but those refunds are entirely discretionary and not guaranteed. Special terms also apply for some countries: https://support.apple.com/108098
Read this support article for information about how long it takes to receive a refund (if one is granted), and how to check the status of a refund for apps or content that you bought from Apple --> https://support.apple.com/118224
