Microsoft said that 40 per cent of the top-15 highest grossing developers in the Windows Phone Store support in-app purchases, although consumer adoption  “varies by market, depending on regional trends, consumer preferences, and other regional differences”.

The company said that the most popular category for the use of in-app purchases was games, which saw more than twice the adoption of the second biggest category, tools and productivity.

But in-app purchases are being used across a wide range of app categories, including books and reference, health and fitness, education, and kids and family.

It was also noted that the strongest adoption has been in central Europe, China, France, Middle East and the US, when measured as a percentage of app downloads.

Looking at the 20 games and 10 other apps with the highest in-app purchase revenue, it was noted that quality is a defining issue – all have a 4-star rating or higher, “and user comments posted in the Store show that users love these apps, and therefore are willing to purchase the in-app items to enhance their experience”.

It was also said that most of these top titles are free (90 per cent), with all revenue generated via in-app purchases. Those that are paid apps “are from developers with a brand name strong enough that users will know the quality or utility of the app”.

Microsoft also noted that 28 of the top 30 are “useful even without in-app purchase”, with the additional purchases used to enhance the experience. “Users feel that they are getting a significant additional value throughout the in-app purchase, and don’t feel forced to buy the app items to be able to use the app”, it said.

Successful developers have also used in-app purchases “as a natural extension of the app, not as an afterthought”.