Recently, a client said a stock photo company had contacted them to request payment for allegedly not having the rights to a photo. The photo had actually been purchased by the client’s previous designer. The client then had the designer get in touch with the stock photo company to show proof of purchase of a license.
If you’re unsure of a photo’s license and usage rights (which can vary greatly), you can find it on the stock photo company’s website. See iStockphoto’s (a popular one) licensing information. Ask your design firm or stock photo company if you’re unsure.