Begin by activating the payment gateway under Setup > Payments > Payment Gateways and choose Amazon Simple Pay from the Available Gateways dropdown.
Once activated, you can then enter the configuration details which can be obtained from within your Amazon Web Services account:
- Click your name in the top-right corner and select Security Credentials.
- Click the "Access Keys (Access Key ID and Secret Access Key)" heading to reveal the API details.
- If a key already exists this can be copied and pasted into WHMCS. If not click "Create New Access Key" and copy/paste the new key into the WHMCS payment gateway page.
Save changes and you're ready to go.
In order to use the Sandbox option you must first contact Amazon Web Services and sign up for a Amazon Payments Developer Account. Once activated, you may then tick the checkbox and WHMCS will connect to the developer account instead of the live business account.