That's how corporations nickel and dime you. I resist subscription services almost completely (I pay for cloud backup storage for my phone in case of breakage/theft and that's it) because as well as being a constant financial drain they inevitably degrade and enshittify, often even removing things you paid for
"Your water subscription has increased by $1, thanks for being our customer. Reminder, creation of public fountains and bottle sharing activities are punishable by law!"
You sigh and delete the email. They send out the same message every month.