The payment needs to be done through the PUCP internal system, which requires an account. It is less complicated than how it sounds! Please, start the process by following this link.
During the payment process, please be aware of the difference between boleta and factura. Unless you are Peruvian and have a Tax Identification Number (RUC), you should request a boleta.
At this time, early registration is closed. From now on, Standard Registration is USD 210, while Student Registration is USD 80. Please, be sure to select the correct option at the time of payment!
Update: If you have already started the process, but for some reason did not complete the payment, you should use this link instead.