Most sites offer some form of subscription service. Ours is currently 3$ a month and less than 5% seems to be using it. Most of our users seems to view it as a donation service though, might be something for any psych-major to do a study on.
Ars Technica recently ran into this, with a major backlash against a Chevy advertorial which wasn't explicitly marked as such. Read the pages and pages of angry subscribers: https://arstechnica.com/cars/2017/07/why-did-chevy-bring-its...