Whether a royalty-free picture of angels – or of any subject – is usable in a commercial publication depends on the type of license its owner offers for its use. The type of commercial use may also be a factor. If the license allows commercial use, the user may need to pay a license fee before using the picture.
Some royalty-free picture licenses specify that the image is only for non-commercial use. Even then, certain circumstances permit using the picture in a commercial publication. If the picture is newsworthy and does not directly benefit the user, as is the case with a picture in an advertisement, it is "editorial use" rather than "commercial use." Editorial use images are usable in commercial publications.
Although royalty-free pictures do not have royalty fees, some have licensing fees. The user must pay the licensing fee before using the picture.
Another consideration is whether the user intends to use the picture as is or plans to modify it. Modifications include adding items to a picture, changing the brightness or coloring, cropping the photo and resizing it. If a license prohibits modification, the user cannot change the image in any way, such as to make it fit into the layout of a publication.
Other rights may limit use of a picture to a certain time frame, geographic location or industry.
Creative Commons licenses may allow use but require the user to credit the source of the picture.