This is a modest investment for a professional billing platform that protects your customers' data and gives you access to support and updates.
When WHMCS detects a nulled installation, its legal team takes action. At best, this means downtime for your hosting company and its customers. At worst, it means formal legal action, civil liability, financial penalties, and the immediate suspension of your hosting account if your provider receives a DMCA notice.
Alex logged into his admin panel, but his password didn't work. The "free" license he had downloaded contained a hidden backdoor