From Showit Desktop Manual

The Showit +Site feature allows you to create unlimited Subdomains for your primary Domain Name using the same account and one Subscription. This can be used to host event and client websites such as

The Showit +Site feature does not allow you to host multiple domain names, each domain name is currently a separate email account and login. Also, according to the Terms of Service you may not resell websites or use your +Sites to host other businesses. The Showit +Site feature is for the use of extending a website with multiple subdomains under the umbrella of the primary domain name.