Generally, the 10 standard assets will get you 10 images, audio, templates, etc., except for video and premium assets. You can also rollover a certain number of unused licenses to the next month. For Adobe Stock video and premium assets, you will need to buy credits.
What Sells Best On Shutterstock?
Some types of photos that sell best are Portrait Photography, Food Photography, Landscapes (usually with people) and fine art photography (artsy).