If don't care about Artists, you probably won't read this. If you do care about Artists, you probably don't need to read this.
So, this is for those who are reluctant:
I can't prevent you from using this Artwork without Authorization. But I'd like to ask you NOT to use it this way.
Think about it. If you use pieces without giving any credit to the Artist, you will be contributing to the gradual extinction of them, as less and less, they won't be able to live from art and will have to migrate to another profession.
So, if you want to contribute with a more colorful and creative world, support Artists.