The e-shop designer "Theme Designer" app, Themes and Tweak services have been around for a long time, and have become outdated, and hard to use.
The new Decorator app is a completely re-designed and re-implemented approach to styling your Ecwid storefront.
Decorator is free to install and try for as long as you like. This means it can be used with Wix which doesn't support paid Ecwid apps.
You pay once to publish your first theme and then you can change and re-publish as often as you like. There is a small annual renewal fee.
During 2017, there are large discounts for existing paid Theme Designer users and early adopters.