You can change your subscription either through the app’s website, or through the app itself.
To change your subscription through the website, you can head to the app’s website and click “Login” on the top right corner of the screen and enter the same email and password that you use to log into your app with.
You can then go to your Profile and select, “Manage my Subscription”. From there, you should have the option to “Change Subscription”.
To change your subscription through the app on your device, you will need to log into your App Store Profile on iPhone or Play Store Profile for Android devices.