Here are a few things to keep in mind about free trials:
- The developer sets the length of the trial. A prompt during the sign-up process will let you know how long the trial will be. Once the trial is over, the App Store will automatically charge your Apple ID's default payment method.
- Going forward, the subscription will auto-renew based on the app's subscription model.
- You can cancel the free trial at any time. You'll need to follow the instructions described in this CNET post. The process includes: opening the Settings app then selecting your name > iTunes & App Store > Apple ID > View Apple ID > Subscriptions. Then, select the app that you would like to cancel your subscription to and follow the prompts.
It’s important to note that the free trial will not end immediately after you cancel it. You can continue to use the trial until your renewal date, and if you change your mind, you can always sign back up for the paid subscription.
According to Apple, if you decide to cancel a free or discounted subscription, it's best to do so more than 24 hours before your renewal date. This will ensure you won’t be charged.