sub-mgr-3.sol

    modifier onlyCreator(uint256 subscriptionId) {
        require(msg.sender == subscriptions[subscriptionId].payer, 'not allowed');
        _;
    }

    function cancelSubscription(uint256 subscriptionId) onlyCreator(subscriptionId) public {
      //delete subscriptions[subscriptionCounter];
        subscriptions[subscriptionCounter].active = false;
        emit SubscriptionCanceled(subscriptionId);
    }