Hi all.  Thank you for your thoughts on the issue of Fotolia.  I did indeed visit Dreamstime to read their terms, and they also offer the purchase of credits in blocks - and sadly, unused credits also expire after a year.  I did write to them for clarification, and asked if I could request a refund on unused credits.  They responded within 24 hours, to say the following: 

Thank you for contacting us.Our policy does state that the credits expire in one year.
However, we always allow a grace period and send you an email a month in advance of when the credits expire. If you are unable to use the credits before they expire, we can reinstate these for one time for another year.

A one-year extension is substantial, although still less than optimal.  I guess the rule of thumb is to purchase the minimum amount possible.  Even this seems counter-intuitive, but at least their reply was prompt, thorough, and professional.  I think I will sign up here after all, and continue to warn my colleagues off of Fotolia.  Thank you again for the recommendation.  I wish you all nothing but success with your businesses.  You have collectively changed the stock image industry by sharing your talents with small businesses like mine in a much easier to use, and more affordable way.