Is the monthly pay by calendar month or every 30 days?

I was wondering if I pay for $19/month, would it include the calendar month, meaning that it would go until the end of October or would I pay for the next 30 days after purchasing it?

When you upgrade your monthly subscription on any day of the month you subscriptions ends after 30 days. Meaning, if you upgrade your account on October 19th your subscription will end on November 18th.

I hope that answers your question. Do get in touch should you need further assistance.