I modeled and textured the ferris wheel for GMod Tower and we reused it in Tower Unite. This is not a free model, this is our model.
We do not give permission to use it, but for GMod (since it's a mod) I have spoken to many people who have used the model and asked them to put credits to us. It's really case by case and ultimately up to myself to decide who can or cannot use it.
Any commercial use of this model is strictly forbidden, of course.