Technically you can use the same PayFast account (that is the same PayFast Merchant ID and Key) on multiple websites. However, using the same PayFast account on multiple websites doesn’t cater for a good buyer experience because the same merchant description (trading as name) would be visible no matter what site you are directed from. For example when a buyer is shopping on site x.com, on redirect to the PayFast payment engine the trading as name will reflect as y.com, the trading as name used to register the PayFast account. Meanwhile from the merchant's side, consolidating payments from multiple websites can be problematic.