I use a service called Privacy [1] to generate virtual card numbers, which I than use with all of my subscriptions. All of the virtual cards are tied to a physical credit card used as the funding source. I get a notification every time a card is charged or a charge is denied (if it's above the set limit or no longer active). This has saved me from fraud where a single-use virtual card # I used to pay for airport parking was used to buy something online and promptly denied and multiple overcharges with random subscriptions. I even started using it for things like gym and utility payments. Highly recommended to keep a tab on subscriptions.