How does the monthly personal license work?

Hello, Could someone explain to me how the monthly personal license works? If I buy it once, by adding it to the shopping cart, I assume it would work for a whole month from the date of buying. What about after that? For the following month, do I have to order it again via the shopping cart or would it be automatically deducted from the payment details I entered at the time of the first purchase? I wrote to the customer service 3 days ago, but not yet received a response. Would be grateful if someone could guide me. Thanks & Regards, Sooraj.