A Goldman Sachs investment note argues that Apple has huge potential for generating more recurring revenue, suggesting an opportunity to generate an additional $7.6B a month, reports Business Insider. The company points to the rumored Apple TV subscription service as one future source of monthly revenue.

In a recurring revenue framework, we have constructed an average revenue per user (ARPU) metric that captures the installment plan pricing of the iPhone ($32/month), assumed installment plans for the other hardware products, and services (e.g. Music at $10/mo, TV at $40/mo) … 

The company also forecasts 40% growth in iPhone sales over the next two years, bringing the installed base to 700M phones.

Although Apple has long offered some subscription services, including iCloud storage and iTunes Match, it is only this year that it has made a big push into monthly recurring fees through Apple Music and the iPhone Upgrade Program.