From Subscribers to Sales: How Doreen Pena Earned Her First $500 With a Children’s Book App

Less than a month after turning her children’s book into an interactive app for iOS and Android, Doreen Pena made her first $500.

Not through ads. Not through luck. And not through Amazon’s algorithm.

This post is a continuation of Doreen’s journey, which began with a simple experiment: what if a children’s book didn’t stop at the printed page?

If you haven’t read Part 1 yet, I recommend starting here: From Paperback to Interactive App: How Doreen Pena Grew 300+ Subscribers Using Her Book.

In this follow-up, I want to break down what happened next — and why this approach changes the income equation for self-published children’s book authors.

From Paperback to App: Setting the Foundation

When Doreen and I first started working together, she had a paperback children’s book published on Amazon KDP. Like many self-published authors, she wanted to take her book “to the next level,” but without creating something entirely new from scratch.

That next level turned out to be an app.

Instead of rebuilding everything, we repurposed what already existed:

• The book’s illustrations
• The text
• The audio

Using Unity, Doreen created a simple MVP version of her book as an interactive app. At this stage, the app wasn’t about monetisation — it was about proof of concept.

Would people actually engage with the story in this format?

The Game-Changer: Building an Email List Inside the App

One of the most important decisions we made early on was to include an optional email signup form directly inside the app.

Using a simple plug-and-play tool (which I teach in this tutorial), Doreen added a form where users could submit their name and email address. This small feature changed everything.

Within less than a month of releasing the app on iOS and Android, she had:

• Over 300 subscribers
• Zero ad spend
• No new content created

The app wasn’t just a product — it became a data engine.

Going All In: From One Chapter to the Full Book

Initially, only one chapter of Doreen’s 14-chapter book was available in the app. That was intentional. Once the early traction proved there was demand, we committed to building the full version. Over the next two months, while the full app was in development, Doreen didn’t go quiet. Instead, she stayed in touch with her subscribers.

Warming the Audience Before the Launch

Doreen’s book is an educational children’s book designed to teach Cape Verdean Kriolu — a language deeply tied to her Cape Verdean heritage. During the eight weeks leading up to launch, she:

• Shared updates on the app’s progress
• Taught small lessons related to the language
• Explained what the full app would include

By the time the full app launched on November 28th, it wasn’t a surprise. People were already waiting. That’s how the first $500 happened — in less than 30 days.

Why This Worked (And Why Amazon KDP Alone Often Doesn’t)

This result wasn’t magic. It was structural.

On Amazon KDP:

• You don’t own customer data
• You don’t get email addresses
• You earn a small royalty after printing, shipping, and commissions

Speaking from my own experience as a children’s book author, I average around $50 per month on Amazon KDP — and that’s actually considered good by self-publishing standards. At roughly $3–$4 per book sale, earning $500 can take close to a year. Doreen reached that milestone in under a month. The reason? Data ownership.

Apps Change the Economics

With a book app:

• App store commissions cap at around 30%
• There are no printing or shipping costs
• The app itself can be free, with paid content inside

More importantly, apps give you access to insights Amazon never shares:

• Where users are downloading from
• Which devices they use
• Which countries are most engaged

That data allows for smarter decisions — including targeted ads that focus only on regions where interest already exists. No guessing. No wasted spend.

Want to Explore Doreen’s App for Yourself?

If you’d like to see how Doreen’s children’s book app works in practice, you can check it out on both platforms:

• Download on iOS (App Store)

• Download on Android (Google Play)

Exploring the app will give you a clearer sense of how the story, language learning, and interactive elements come together — and how the app experience differs from a printed book.