To explain what commercial use means - no matter if someone buys you a thing or you get it on your own, if you use it to sell a product (which could happen if you use such thing as a tool or an asset), that's a commercial use. If you buy a game and play it, you aren't using it commercially. Now if for some reason you would decide to modify it or use its code for your own product and then try to sell it, that's commercial use.