Currently, we are developing an android app, which is used to target stock market investor.
May I know which way offer a better way, to monetize your app?
Pricing Customers Monetization Android
On Android, you are going to have problems gaining revenue from any app, compared to iOS (Many, many people have an iTunes Account with a linked credit card. Many fewer have a Google Wallet account).
That said, targeting the professional market, if you have a truly polished product, you should make the app a paid app.
Conversion rates are very small anyway for freemium apps that are not games.
With such a specific target group (stock market investors), I would leave those two possibilities. Why?
Usually, stock market investors are (+/-) wealthy population group. If they buy a "tool useful for their activity" (= making money), that means that tool bring them some money. And in that case they probably don't care for $2 or $5 for the App. In the contrary, it is possible that such a price makes your App less credible.
What can be an alternative way to monetize your app, is to include it in some kind of package. One example: create a website about the problem your app is solving, put some more info and make the access to that website paid (one single fee or some periodic subscription if you can provide a flow of useful information) - and the App can be "for free for the members of your service".
Bring the value and don't fear asking for what it worths! Analyze your customers and you will see that a businessman having a $1M stock portfolio will probably not be interested by a freemium app where he has to pay $2 for a "chest of coins" or a "handle of technical analysis tips"...
I know that paid apps do not sell well, so unless its a specific app that a user really must have to do some task, chances are they'll walk past it.
So the alternative for the majority of apps is in-app purchase, but these require a vast number of users, I understand the rate of people spending money in-app is in the low % (eg 1-2%) for even the best apps, so you need millions to make it work. That, of course, requires a certain type of app and infrastructure to run it.
The 3rd alternative is advertising, this is much more common for Android revenues. You can offer a paid version that removes all ads which seems to be a valid business model. Casual users will try it out with the ads, then if they user it they will pay to get rid of the annoying flashing things.