: By Click Downloader licenses are typically valid for one computer. If you've recently upgraded your hardware or switched PCs, your key will stop working until it's reset. You can Reset your Premium Account using the official YouTube by Click reset page by entering your PayPal email and activation code.
Sometimes activation servers block known VPN IP addresses to prevent fraud. Turn off your VPN and try activating again. byclick downloader activation key fix
Once your key works, keep it working.