Hey, sorry I don't have an official license yet, as I'm not sure which one best fits, but in general now that you've paid for the asset you are free to use it in any commercial product, and modify it in any way you need. I just ask that you credit me in some way for the assets. You can't resell just the assets on their own.
I'm going to look in to finding an official license to use in the future, as you're not the first person to ask. I hope this helps!
-Ashton