These notifications are bundled together for some reason. So if I want to be notified when my subscriptions renew themselves, I have to also be notified of random games going on sale, too.
I completely disabled all notifications from Google play. There isn't a single one worth of it.
That said, when I open it (like once every 2 months) I have a permanent dot on the notification area, with a notification that goes about 'plz enable notifications so we can spam you'