Expired app means that the review time of the app developer account has expired or the app has been updated. When running some software, signature verification is required. If the software is not signed, it cannot run on the system. If the APP expires, you can directly obtain the developer's account at this time and use it again after authentication. For example, the signature of the App used is charged monthly, so one month has passed and you can't continue to use it without renewing the fee. Benefits of APP signature application upgrade. If you want to upgrade the version of the application, you must sign it with the same certificate, because the system will only allow you to install and upgrade this application if you sign it with the same certificate. If Apple shows that your application is out of date,