I would not copy Everand's subscription model without their catalog deals. Reading subscriptions are content businesses wearing software clothes. The model is the easy part.
Without books people want, you are selling an empty shelf with autopay.
What matters
Exclusive or broad rights, discovery that surfaces the right book, churn after the free trial, and unit economics on royalties that still work when the growth team stops buying installs.
Startups in digital reading
Niche verticals can work: professions, hobbies, languages.
General "Spotify for books" is a graveyard.
Lessons without copying
Bundle when you have depth.
Price for habit, not one download.
Invest in onboarding to second book fast.
Everand news is a reminder that subscribers pay for libraries, not apps. Build or license something worth renewing.