You are responsible for transferring ownership of your new domain name by ensuring that your contact information is listed in the whois database. The cost incurred upon purchasing your domain name is a one-time cost. Nonetheless, once you have purchased your new domain name, you are still responsible for paying the annual registration fee. For this annual registration, you must ensure that your chosen registrar is able to contact you, and that you pay the registration fee directly to them prior to expiration. Registrars are required to attempt to contact the administrative contact prior to a registration lapse, but ultimately it is your responsibility to ensure that the registration is paid up.