Shutterstock images are now available via an 'on demand' subscription (a package of downloads which can be used over the space of 1 year - pretty much the same as the pay-as-you go or buy credits systems offered by other agencies).
While its not a ground-breaking sales model I'm sure it will increase shutterstocks' sales. I'm certain that there were casual/individual designers who were put off by having to fork out $249 for a month long subscription, and for who the option of 25 daily downloads is too many.
With most of the other stock agencies moving in on shutterstocks subscription model (but seemingly not bettering it), it's easy to see why shutterstock have made this counter move. Most of the major sites now offer 'something to cover all bases'
Below is a quick reference from the shutter stock site:
external link: shutterstock.com [4]