I want to cancel my subscription but it is not showing in my subscriptions

Did you subscribe directly? In that case you'll have to contact the developer of the app and cancel the subscription.

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• If you can't find a receipt from Apple for the subscription, you might have bought the subscription from another company. To find out which company bills you, check your bank or credit card statement. To cancel the subscription, you must contact the company that bills you for the subscription.

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copied from: If you want to cancel a subscription from Apple - Apple Support