[QUE] How do Short URL Makes Money?

I see there are many websites for short url like adfly etc. I can understand about some old website like adfly and others. But how do new short URL website makes money? I see there are less opportunity of advertiser for them. Some of them are running adsense, but it can be banned anytime.

In the past there were some PTP websites, but now a days they are also not active.

So how do you think they are making money?

by pankajjangir via TBN