amazing question. Relevant to me right as I look for a developer myself.

There are not a lot of people looking for app developers, so ads would have been the last thing I would have suggested.

An easily scalable business model is to hire local sales contractors to find and funnel leads themselves in exchange of sales commission. They become 1099 and you only pay if they sale. You can create a site or squeeze page that reflects their local market but besides that your marketing costs will drop significantly while sales should increase that much more, as I often find their results directly proportional.

Best of luck!
Humberto Valle
#UnthinkStrategy

Do you want to be a service based agency or is this a standalone startup . I founded agencymobile in 2006 which was The first iOS developer in Europe . Happy to help if you can clarify a little more of your business

At 3M+ Impressions per day what is your exact fill %? Also what is your breakdown of impressions by platform You can potentially look to other ad partners to fill your supply. You can either plug into other ad-exchanges, the inventory that is not getting filled. The business model is the same, you are selling ads on CPM basis, you essentially just need to plug in the best ad SDKs as possible to fill as much inventory as possible.

Google Admob has relatively decent targeting, however, there are other options to ensure you get a high fill %.

My advice would be to plug your ad inventory into the exchanges. (e.g. Mopub, etc)

It is difficult to say ‘THE BEST’ one, because if it suits you, it is best for you, and if it does not suit you it is not best for you. Here are few models that most mobile application are based upon:
1. FREEMIUM: It is one of the most favoured ways of monetizing your app by offering it for free. But the users need to at least once purchase it to receive all the benefits from the app. While using music, antivirus, or such mobile applications, you must have noticed that several ads get opened without clicking at any button. This occurs because the apps use the uses a freemium model. The users are more likely to spend cash on an app’s premium features by offering the app for free.
2. FREEMIUM APPS THAT ALLOW MULTIPLE PURCHASES: Just like the basic freemium model, a multi-purchase freemium app allows users to put more money while using the application. This thing is usually has been seen in mobile games. This model instigates the users to keep spending money on their free app by offering additional game items. And many of the addicted users keep pumping money into the game to advance their rankings. Making money via mobile app depends on the model means which business model you have selected for your mobile app development.
3. ADVERTISING ON FREEMIUM APPS: Advertising is the ultimate idea for any app publisher. This model offers the app for free if the users can endure banner ads, or simply they can purchase a premium version without having these disturbing ads. The publisher will be benefited on both occasions. By running an advertisement for the mobile app or on the mobile app, you can build, or cam grow up the market value of the application.
4. PARTNERING WITH A SPONSOR: Unlike the old ways of advertising, where several ads from various companies keep disturbing, so to eliminate these types of issues, many apps have made partners to a particular sponsor. Only the ads pertaining to a particular sponsor are shown in these kinds of apps. This also helps your businesses in targeting the audience. If your business relates to any brand name, this model will be helpful for your business.
5. VIDEO ADVERTISEMENTS: In this method, instead of just showing a banner ad of your app, you can show a short video to the customers, which is more appealing and attractive. The app developers’ partner with ad networks to make and show short video ads on their apps, which will help generate revenue.
6. PROMOTIONAL SERVICES: Without any promotion, you are surely not going to make a single penny from your mobile application. Even films need to be promoted to earn more money. You can simply promote your apps by using promotional services like Appshout, by which your mobile app will be visible to many consumers and app reviewers. Even getting your app on famous websites and social media can help it grow more. This will amazingly help your app in getting the making app ranking on the first page.
7. PAID APPS: It is easy to guess that this option means paying for the app from the very beginning. It is a business model that has the potential to make money. To make this method working, you need a brand or recognized product with devoted users, or you can also use promotions to show your app to your target audiences. You can also build such apps that everyone wants, or you can also build an app as a service app; for example – Uber, Zomato, Swiggy, Ola, etc.
Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath