If you've purchased a stock photo to use as your cover photo for Facebook, LinkedIn, Twitter or Google+ (or any other social media outlet), be sure you understand the licensing terms.
If you have purchased it from iStockphoto, note that you can only use it:
"...for advertising purposes, and as long as it is modified (like modifying the image and/or adding text to it). Adding an unmodified image to a fan page as a profile picture, a timeline cover or as a background image is not an acceptable use (unless the image has been modified)..."
We had recently contacted iStockphoto with an acceptable use question, and they provided us with this clarification, and we thought our customers would find it useful as well.
In addition, it's against most stock image providers' terms to present the photo in such a way that it appears that the model in the photo is endorsing a product or service. An example of this would be using a stock photo of a person next to a testimonial from a customer. This makes it look like the model said those words, and would be against the license agreement.
If you're a Banyan Theory customer, and have a stock photo image that you'd like to use, but don't have the software to make any modifications to it, contact your Account Manager to inquire about assistance with your project.