When you set up your WebsiteLock account on a domain name (more info), it will scan that domain name's website, as well as all of that domain name's subdomains.
For example, if you set up WebsiteLock for coolexample.com, it will also scan blog.coolexample.com and store.coolexample.com.
However, if you want WebsiteLock to scan separate domain names, you need to purchase WebsiteLock credits for each domain name here.
For example, if you wanted to scan coolexample.com and coolexample.net, you would need to purchase two WebsiteLock credits.