Does your apps stay with your email on iPhone 4?

What I mean by this if you get a new iPhone/iPod/iPad if you use your email for the app store. Will you keep the paid apps you had if you did not bought it on the email you are using? So basically you bought a app on some other email but you ( Example - forgot about the email you can't remember anything about it ). Then you use some other email, then something happens like if you have to reboot your phone or buy a new one for a certain reason will you still have the paid apps on the email that you didn't bought it from?

You mean Apple ID. You have to use the same Apple ID on the new device as on the old one, if you want to be able to re-download your old app without having to pay for them again.

If you wanted to re-download prior purchased content from the store you need to be able to sign into that account and have that password. Otherwise you're not able to get into the account to get that stuff.you're out of luck then.