Ios app weird free but purchased?

So there was this app… I emo pro or something like that, but it says free, i hit download and it failed to download, instead of daying install there was the cloud this time, when inpressed the cloud it said i already purchased it and began downloading, it said free though, but i checked and the credit catd wasn't on there so hooefully it was free, but does anyone have any clue to the reason? This is on iphone 4s btw

As long as you did not put your credit card details, it should be fine.