Keep widget in memory

I have a simple android widget with a button. If app is not running (or not in recent tray) button click takes few seconds to work. But if the app is running button click works instantly.

Simple approach would be to use service to keep my app in background. But i am not sure how to achieve that. I mean i know how to implement service's in android.

Using a service that's actually not doing anything. Is this the right approach do this? I haven't found any other solution online.