I had an account with them as a software developer (a merchant account then). When people purchased other items a license of my software could be selected as a prize and I would receive a few dollars for that.
Since sales were rare I asked Trialpay to pay me the balance of approx. $50 to my Paypal account and cancel the account. Request it 3 times and never received any answer from them. For me Trialpay is a total scam organization. Keep a distance from them.