How does a metered paywall track its users?

Question

A metered paywall is most seen on online newspapers. It allows users to view a specific number of articles before requiring paid subscription. In contrast to sites allowing access to select content outside of the paywall, the metered paywall allows access to any article as long as the user has not surpassed the set limit. 

I've done some research and it seems that you can bypass these paywalls by using private browsing/incognito mode. I'm still getting familiar with how the web works, so have some patience me.

If you can easily bypass this by deleting your cookies and stuff. Why can't websites just track users by IP addresses?

Answer 1

Because IP addresses are not a good way to track individuals. NATting (Network Address Translation - used to provide private [e.g. 10.10.X or 192.168.X] IPs internally and a smaller number of public IPs externally) means that any individual IP address could be masking dozens, hundreds, or even thousands of unique people. If you implemented a metered ban of 10 articles and 10,000 people have the same public-facing IP address, you would blow right through the limit in a few seconds or minutes and present the paywall incorrectly to X numbers of users for the remainder of the metered period. That's fairly user-hostile behavior and not recommended as a brand-builder.

On the other hand, you are willing to live wih a certain amount of "theft" from the more technically savvy members of your audience because the vast majority of users don't have a clue how to get around the meter. Better to "lose" a few subscribers to superior technical knowledge than lose an entire multi-national company's worth due to poor decisions.