4)  Paste the "Client Key" and the "Service Key" from your Worldpay to your Payrexx account.  Switch between test and live mode.  Add or remove payment methods.  Add or remove currencies.  Paste live API keys from your Worldpay account. This can be done once Worldpay approved your application and enabled the "Live or Productive" API keys for you. Always remember to click save after updating the settings.