When you buy a plan/domain, subscription is activated automatically (in most cases).

Please see more information on these related page:
How to manage Subscription?
How to cancel automatic renewal when paid with PayPal?

If you was charged by Site.pro and you are not sure what exactly for, then take the following steps:

1. Create new ticket;
2. Specify all possible details about transaction:
   • transaction amount and currency;
   • transaction ID;
   • transaction date;
   • used payment gateway;
   • if possible, attach the invoice to the ticket.