Hi Vincent,
I am not the component creator, but have worked in the past with Kendo libraries. What I recall is that Kendo-ui Core is opensource. So it depends on if the Forge component is only using kendo-ui core components, or also components that are only available in a commercial license.
Looking at the description of the component, I would say that it does require a license as it used the Kendo UI Drawing library which is not part of the Kendo-ui core.
https://docs.telerik.com/kendo-ui/framework/drawing/overview
When checking the Kendo libraries included in the Forge component, it turns out it even uses the complete Kendo-UI package which for sure is not free, the comments of the library also mention that.
I think the component owner should state this more clearly in the component description.

Regards,
Daniel