DesktopMMD4: Born to Dance is free to use, so you don't need to activate it with a license key. However, you may need to register on the official MMD website to access additional resources, such as character models and plugins.

Searching for a "Free Download" of this software from non-official sources poses significant risks:

The DesktopMMD series generally receives positive reviews from the niche community of desktop customization enthusiasts.