Problem getting unity game trough xcode to device.

I Can only run my game on a simulator but can't get it to my iphone device. I get the error: " Code Sign error: The identity 'iPhone Developer' doesn't match any valid, non-expired certificate/private key pair in your keychains " . Will that problem solve if I buy The IOS developer program for iPod, iPhone and iPad :
( https://developer.apple.com/ios/renew/index.action ) . Or is it something in the settings that I must change. Because I don't want to waste money for something that I don't need. But I can change the unity player setting to SDK Simulator and then it works on the computer screen. But not on device

Pleas Help.