It's difficult to summarise the key lessons but you need to consider things like:
* What does having an API allow your customers to do?
* How valuable is that?
* Are they willing to pay for it?
* How do you align payment to the value?
* Is an API considered "table stakes?"
The book I linked goes into more detail so I really encourage you to read it. You can skip over the organisational changes it recommends, just the principles of pricing are good enough for your use case.
Sadly, I haven't seen anything literature on real value based pricing
1) Customers don't care about the technologies you're using, the elegance of your XYZ algorithm, or the novelty of feature ABC. What they care about is solving some problem they have, making their day easier, becoming more productive, etc. When you're pitching your product, talk about how it helps the customer, not about how it's built. A great 5-minute video on this is "Understanding the Job" by Clayton Christensen: https://www.youtube.com/watch?v=f84LymEs67Y
2) Think about monetization early on. Like most engineers, I had dozens of side project and business ideas. For each idea, I had thought about the features I'd build and how I'd build them, but not the business viability: who would I sell to? What would the pricing model be? How much money would that translate to for a typical user? Would users have the work/personal budgets to pay what I wanted to charge? Was the price enough to cover marketing and user acquisition costs? I haven't read it, but have heard that a great book on this topic is Monetizing Innovation (https://www.amazon.com/dp/B01F4DYY1I). Another good book to think about business models is The Art of Profitability (https://www.amazon.com/dp/B000FA5TTM, brief notes: https://codingvc.com/the-art-of-profitability)
3) Finally, think about marketing and customer acquisition in parallel with product. After almost 5 years as a VC, I can readily confirm that most products don't sell themselves. Even the really good products need sales, marketing, etc. A great book to get started on marketing is Traction by Gabriel Weinberg (of DuckDuckGo) and Justin Mares (https://www.amazon.com/gp/aw/d/B00TY3ZOMS/)
Basic idea is that you should design the product around the price. Do price discovery before you do anything else.
Podcast ep here: https://www.youtube.com/watch?v=A6veeCbKIzw