Stream Deck Mobile offers a 30 day free trial, after which a monthly or yearly subscription is required. This subscription can be cancelled at any time. Cancelling the subscription is not done in the Stream Deck Mobile app.
Below is the information about cancelling a subscription on an iOS and Android device.
Cancelling Stream Deck Mobile Subscription on iOS
1) Open the Settings app.
2) Tap your name.
3) Tap Subscriptions. (If you don't see "Subscriptions", tap "iTunes & App Store" instead. Then tap your Apple ID, tap View Apple ID, sign in, scroll down to Subscriptions, and tap Subscriptions.)
4) Tap the subscription that you want to manage.
5) Tap Cancel Subscription. If you don’t see Cancel Subscription, the subscription is already canceled and won't renew.
More information in this Apple support article: https://support.apple.com/en-us/HT202039
Cancelling Stream Deck Mobile Subscription on Android
1) Go to play.google.com.
2) Check if you’re signed in to the correct Google Account
3) On the left, click My subscriptions
4) Select the subscription you want to cancel.
5) Click Manage > Cancel Subscription
6) To confirm cancellation, click Are you sure you want to cancel?
More information in this Google support article: https://support.google.com/googleplay/answer/7018481