Most IPTV Reseller Panel platforms have a "trial credit auto-refill" setting. It's often on by default. I've seen a reseller lose £300 because his panel kept giving trial credits to the same MAC address every 24 hours. A customer discovered this. He watched British IPTV for free for three months. The panel never flagged the pattern. The reseller never noticed until his balance hit zero.
What actually works is a panel with per-MAC trial limits. One trial per device. Ever. Run a British IPTV trial test through your panel. Use the same device to request a second trial. Does your panel allow it? Does it warn you? One reseller I know sets his panel to block any MAC address that has ever received a trial, regardless of expiration. His IPTV Reseller Panel also notifies him when the same IP address requests more than three trials in a week. That catches abusers early. That said, most panels assume good faith. Assume bad faith instead. Configure trial limits like someone is trying to break them. Because someone is.