It's unclear to me how many "assets" are needed for most of the stock photos at Adobe Stock.
Is it one asset for one image, or several assets for one image?
A standard asset refers to images, 3D assets and templates. So, if you have a 10 standard assets per month subscription you can license 10 standard assets.
If you are looking to purchase Premium images or videos, they would need to be purchased individually on demand.
Common Questions, Adobe Stock for more information.
Hope that helps.