I’ve turned very sour to these monthly renewals and accounts I can’t keep track of anymore.
Similarly, if I'm on the fence about some service, this is the tie breaker for me; the risk of forgetting to cancel it. Even though I do scan my bank account around once a month, I do naturally pay more attention to the bigger transactions and can easily skim past a $8.99 for a few months before noticing I accidentally left something on.
(Fortunately, where I am, it's just an annoyance. Affording individual subscriptions to all the things I may conceivably at some point want to use would be a noticeable kick in the pants, what with the proliferation of them, but accidentally leaving on one service is just an annoyance.)
If I somehow still need it after the first month, I usually get a email reminder or a message about payment processing failure and I can fix that with a non-disposable card.