1D's Story of my life has been at the top for days, but it was released like 2 or 3 weeks ago reaching top then going down, did the Directioners start some petition to get them their 4th no1 or something? Or just got slot of air play recently?

I don't think there is any petition of any kind... But the song was launched with an on air/on sale strategy, and then got playlisted by both radio 1 & 2 as well as others, and it's still getting airplay from what I understand.
I suppose if it had been promoted before it went on sale, they might not have kept it playlisted for so long after release, but that's how things went: not so strong debut but relative longevity.

it's a superb, emotional song co-written by the boys that really tugs at the heartstrings... no wonder even those who initially didn't like 1D are confessing to enjoying this song