Q: Why FIFA 15 is not on app store?

You will have to contact the vendor, this is an Apple user forum

You can also try to get to your App Store app > Purchased and scroll until you find it so you can install it, should they have not removed it from the App Store.

if it was ever in an ios version then could be EA sports pulled it when they released fifa 16 in which can you can only get it if you bought it before they pulled it

This is a user forum. Feel free to leave feedback to Apple

http://www.apple.com/feedback/iphone.html

And again contact the vendor (EA) as we can do little more here.

Thank you a lot man!!
It's worked

Help FIFA 15 is on my purchased list but my apple ID has been disabled but i made a new Apple ID but it's not there I can't get it the only way is with my other Apple ID but it has been disabled  

Then fix it... If your Apple ID is locked - Apple Support