You sometime have to migrate a production app to a different Google Play account, when for example your company was acquired.
Once the app has been migrated, the service account used to access purchase information by Fovea will stop working. So you need to setup a new one. The “billing key” doesn’t change, so that the only change you should get prepared to perform.
Make sure you alert your users that in-app purchases might be dysfunctional for a few hours. Once the new service account is setup, things will quickly get back to normal.