How can I earn money online by part-time jobs without any registration fee?

I am 17 yrs old and I have started using the iPhone/pad app "app trailers."
All you have to do is downloaded the app and enter my bonus code gwilli74
And you will receive 50 free points. This app allows you to receive money or
Gift cards in return for watching app trailers . I use this app about 30 minutes a day and get approximately 50 dollars,if you do the mathe that is 100 dollars an hour