You have to watch videos and download apps or one can do the surveys to earn money. It sounds easy but it is very difficult to achieve the minimum payout which is 2.5$.
1000 points is 1 dollar. Watching a video credits 2 to 5 points and that is also based on luck. Sometimes they credit and sometimes they don't. And you can't even complain them regarding this as there is no history records which mentions that the video was watched. Also the number of videos that one can watch per day is limited.
They also pay for downloading the applications . Most of these apps are not available on playstore and have to download via veb browser. I downloaded some of them. And my phone was filled with advertisment popups and auto downloads of apps without my consent. These apps hanged my phone to that extent that I had to factory reset the phone.
Talking about surveys, they wont make you eligible for 95% of them. And the 5% survey which you will complete they will reward with 15-20 points.
Accumulating 2500 points will take more than 1 month, and 2.5 dollar a month doesn't make any sense.