Snapchat has run its first app-install ad - a big sign the app is revving up its monetization engines

Snapchat ran its first app-install ad on Thursday, Adweek reported.

The ad, for SNG-owned mobile game "Cookie Jam," ran within the iHeartRadio channel in Snapchat's Discover section. The video spot encouraged users to swipe up in order to download the game.

Snapchat declined to comment when contacted by Business Insider.

The rollout shows Snapchat - which has famously taken a softly, softly approach to rolling out advertising products - is once again moving to emulate its digital media rivals when it comes to monetization. Recently, the company improved its ad targeting and measurement options, for example. It is also reportedly eyeing a move into ad tech.

App-install ads are big moneymakers.

BI Intelligence estimates that spend on mobile app-install ads in the US alone will reach $5.4 billion in 2016, rising to as much as $6.8 billion in 2019.

The huge growth can largely be attributed to the fact that most of the time spent on mobile phones is within apps - so marketers and developers are prepared to pay a premium price to attract users. It's also relatively easy to measure the return on investment of this type of direct-response ad, compared to other forms of online ads.

BI Intelligence predicts 30% of total mobile advertising revenue last year was generated by app install ads. And while Google and Facebook have never publicly released mobile app-install ad revenue numbers, it's estimated that a huge proportion of their mobile advertising revenue is made up from this format. The Information pegged Facebook's mobile app install ad revenue as $3 billion in 2014, or one-third of its total revenue.