Shopify released their new Subscription API and have now removed any apps that bypassed the Shopify Checkout.
They have put together a collection of apps that now support Shopify Checkout
The announcement said that any apps already installed were ok, but no new installs. So you'll either have to wait until the app developer to update the app or move to a different one. I suspect the removal of all the reviews was because the app was effectively removed from the app store and a new version was submitted by Bold to replace it.