Usually when someone downloads an application for free or a fee from Appstore on your iPhone, you will be asked to enter the password for the security features of the operating system iOS. If you feel it’s annoying and unnecessary, Apple also allows us to turn it off by simply following.
First, on your iPhone go to Settings.
Find and select iTunes & App Store.
Then you click on the Password Settings section.
Finally, in Section Require password you turn it off as done.
Hopefully these tips help you in the process of using the iPhone, wish you success!