It was called Shopkeeper, and I don't remember the name of the app they purchased but it was subscription-based (this was long before the in-app subscriptions)

It was called Shopkeeper, and I don't remember the name of the app they purchased but it was subscription-based (this was long before the in-app subscriptions) and supported more than just Shopify. Developing for Shopify was great. Their API is good to work with, and they're very developer-friendly in general.