how to prevent the application from jail breaking

Hi all ,i have a android application which is ready to release .so to release i have put the app in android market .the user can buy the app and can install the app into the phone.android market wont provide any apk file to the user .so normally we need not bother about re distribution of of the app to the unauthorized persons(who didn't buy the app).


But what my problem is ,I heard that there is a jail breaking concept which can allow the hacker to get the apk file(installation file) from the device .(even though android market not giving the apk file to the user ).

then he can distribute the apk file to all(to unauthorized persons ).how to avoid it.is there any thing to restrict the unauthorized person in using our app,even though he get the apk file .

does android market provides the details of the users who has buy the app by paying ?
like his IMEI number or his gmail account , or etc;


its very urgent if any body knows pls give me any idea .

thanks and regards

Murali dhuli