If you own the domains, then you can go with the standard license. As long as you are the owner of the domain, you can use it on unlimited URLs.
If you were selling the websites, or doing them for other people — then you'd need the developer's license.
Also, we just launched Market Theme version 4.0. It's a major design change over the previous 3.62 version. The demo website is still setup with version 3.62.
So, when you get into the download center you'll see both versions 4.0 and 3.62, so you can use whichever version you visually like better.