This stock is distributed under the Resurgere Stock License. As such, commercial use of this stock item is strictly forbidden, unless you have prior permission from the Resurgere Producer of the stock item. However, you are allowed to use Resurgere stock in your noncommercial projects.
Bones are pretty easy to come by if you spend time walking in the wilderness. You can also find places to buy ones that might be in slightly better condition. This whole pack, is pretty much just one skull. Got a lot of mileage out of it.