I was tiring to build an app which uses google maps for showing places and Pace API for searching places. but it is not being possible to build the app with two different AP
yes you can use same key for both services
http://javapapers.com/android/find-places-nearby-in-google-maps-using-google-places-apiandroid-app/
https://examples.javacodegeeks.com/android/android-google-places-api-example/