How do I detect when my purchases have been 'restored'?

I am using the Mobile IAP Restore Purchases command on Android but how do I know when this has been done successfully/or not?

I tried 'On Product #### purchase success' and 'On Product #### owned' but they dont seem to work. These only seem to work when I make the initial purchase.

Do I even need a restore purchases button theses days?

Thanks

You don't need it on Android.