Enhanced licence - purchasing for one off print

If you license the asset for a client, who wants to print a poster for his own use, you are good with a standard license. If a different client chooses the same picture for his use, you need to relicense. This is independant from who does the printing for the customer. The customer cannot do merchandizing with the asset.

If you are doing merchandizing, like selling posters of one epic stock image, YOU need to licence the asset for YOUR own use under an enhanced licence and you can print as much posters as you can sell. 

Look here for more information on licensing: https://community.adobe.com/t5/stock/links-for-licensing-terms/td-p/11366788
(Disclaimer: As always with licensing, this is my interpretation of the rules. I think they are correct and advice is based on reading and interpreting the licence terms and on fair use for both the buyer and the artist/stock company, but I cannot rule out that my interpretation is wrong. I'm not an Adobe employee).