Most payment systems process transactions instantly after the confirmation's been received, or within a business day. Not all of them, though, and not in every case. The actual completion time depends heavily on the payment provider. Usually, the terms are specified on the provider's website or displayed during the transaction order.
If your payment remains "Pending" for more than 1 business day, or it is completed, but the funds have not been credited to your account, please contact us at email@example.com or in the live chat.