Your subscription begins when you activate your first piece of paid hardware. This includes our CloudBox and any Tank Monitors. When you add your second or third product or service to your subscription, we prorate that charge so you only pay for the time until your subscription renews. Any changes you make to your services will be added to your next invoice.
For example, my subscription renews on the 19th of every month. Normally, a Morrison Bros Tank monitor is $10/month. If I activate my Morrison Bros Tank monitor on the 28th of June, I'm only charged for the time between June 28th and July 19th. This turns out to be $7.02. I will see $7.02 added to my invoice on July 19th. Every month after that it will be $10.00.
Our invoice will include the phrasing "Remaining time on Morrison Bros Tank monitor after 28 Jun". It helps for me to read this as "Remaining time until your next subscription on Morrison Bros Tank monitor after 28 Jun".
Hopefully that helps clear things up!