Licence:
You're free to use this song in any of your videos and monetize as well but you must include the following in your video description.
Alex G:
http://www.facebook.com/helloalexg
http://www.twitter.com/alexgmusic7
http://www.instagram.com/alexgmusic7
http://helloalexgmusic.tumblr.com
Katy Perry:
https://www.youtube.com/user/KatyPerryVEVO
Music Link: https://youtu.be/gzZIKJuVB7o
Music provided by Royalty Free Music [RFM]: https://www.youtube.com/rfmofficialpage