You can download a fully functional free trial directly from the official ClamXAV website to test the software for 30 days without needing a registration code.
Unofficial versions often cause system crashes or scan hangs. ClamXAV Antivirus Version History and Release Notes
If you have already purchased the software but lost your details, you can use the Lost Key Retrieval service to have your registration key resent to your email.
Subscriptions start at approximately $29.95 for up to three devices, which provides verified protection and regular security updates. You can purchase a license through their online store or directly within the app.