Using one Google Maps API key for different android applications

You can use the same keystore and the API key for different applications.

1. Use the same key to sign your apps.
2. Add a line for each application in the Console page.

So, something like this:

BB:0D:AC:74:D3:21:E1:43:67:71:9B:62:91:AF:A1:66:6E:44:5D:75;com.example.android.mapexample
BB:0D:AC:74:D3:21:E1:43:67:71:9B:62:91:AF:A1:66:6E:44:5D:75;com.example.android.anotherapp
BB:0D:AC:74:D3:21:E1:43:67:71:9B:62:91:AF:A1:66:6E:44:5D:75;com.example.temp.lastapp

And now, you can use the same API key with all these apps.