To deploy and run an Android Application package (.apk file) on physical devices, you need to sign it with you personal signature (certificate). Based on this signature, the Android system identifies the author of every deployed application. You do not need to apply for a personal signature to any authority, a signature generated by IntelliJ IDEA is quite sufficient.
Use this Extract a Signed Android Application Package Wizard to have IntelliJ IDEA digitally sign Android Packages (.apk files) during package extraction. You can use previously created signature keys, create new ones in existing keystores, as well as create new keystores.
Alternatively, configure the .apk file as an artifact by creating an artifact definition of the type Android application with the Release signed package mode turned on. When IntelliJ IDEA builds the package in accordance with this definition, it signs the package automatically.
An unsigned package is used when you want to test your application on an emulator. Unsigned packages can be extracted only through artifact definitions with the Release unsigned package mode turned on.
You can also extract and sign debug packages. This is sufficient for testing and debugging applications but does not allow publishing them. Signing packages in the debug mode is available only through an artifact with the Debug package mode turned on.