Providing a credit to the artist for the image(s) is not only abiding by the license agreement, it also gives you the appearance of being more reputable. When your customers notice that you are being on the up-and-up with the artist, they can assume you are being on the up-and-up with them; therefore they may place more trust in your company, your products and your ethics.
For Online Use
Copy and paste the following code to your html or css document:
<a href="http://www.bgagraphics.com">Images © BGA Graphics.com</a>, Licensed to YourCompanyName.
Agreement: "3. You can't use them online unless you give a credit link to this site for the original artwork. Include the link on each page you display the image or your product with the image on it."
For Printed Use
Note: If the item you're placing the image on is too small for the text, you can include it on the packaging. For example, a Christmas ornament with an image on it would not have room for the text, but the packaging would. The credit is not required for business cards.
Images © BGA Graphics.com, Licensed to YourCompanyName.
Agreement: "2. You can't use them for your business unless you give credit to this site for the original artwork."