iStock has nothing to do with Adobe Stock. I am not sure what you are asking?
Dear Brad, I download the image by Adobe Stock, I have the licence, but i dont know if I can use the image for print t-shirt or other articles.
If you are selling the t-shirts or items you will need the Extended License.
here is the license agreement: http://wwwimages.adobe.com/content/dam/acom/en/legal/servicetou/Adobe-Stock-Additional-Ter ms_20160119.pdf