Don't remember purchasing anything

I am currently using iPhone 6 16GB for almost 11 months and all of sudden I was checking my Balance of my bank card and It says that I purchased something worth 12SGD$ which I do not remember anything about purchasing this stuff and I have no idea what kind of application it was for. So my question is can you guys please help to see what kind of application it was for? and it would be so nice if this is done faster because I already went to my bank office about this issue as well and they are going to investigate a lot of things which I might not have a time for so it would be really nice if the feedback direct. Thank you.