Про печать на футболках и лицензии:
Shutterstock’s Enhanced License allows you to use images on Merchandise for sale or promotional distribution. There is no restriction on the manner in which the merchandise is produced, whether inventory is produced up front or merchandise is created on demand when ordered by the customer. On demand products include, for example, merchandise like t-shirts that are printed once a customer chooses the design, size, and color.
и ещё раз об этом:
To sell merchandise that incorporates Shutterstock Images, you'll need our Enhanced License. The Enhanced License allows you to use Images on merchandise, both that you sell and that you give away for promotional distribution, with no limit on the number of copies produced. Some examples include coffee mugs, hats, t-shirts, and calendars. Note that for posters, the Image can't be the only element displayed; it must include some kind of graphic/design element.
С шаттеровского блога инфа, если что.