Mobile in-game purchase revenues will top US$4.8 billion in 2016, more than double the 2011 total of US$2.1 billion, according to Juniper Research. The analyst firm suggests a growing acceptance of in-game purchases, combined with the sharp rise in smartphone adoption, will fuel an increase in the sale of in-game items over the next five years.

As users become more familiar with the freemium model – in which games are downloaded for free but can have additional features added for a small payment – the proportion of players who buy in-game items will increase. This will be most obvious in the social and casual gaming category where free or low-cost games are expected, the research firm said.

The number of developers using the freemium model will also increase as they move away from the pay-per-download-model with free games being downloaded in greater volume. In-game purchases should also reduce piracy as purchases will need to be verified by the developer themselves.

However, the freemium model may not always be the most lucrative. “While some games may generate significant revenues from in-game items, the model doesn’t work with all games and developers have to tread a fine line between encouraging purchases and appearing to be exploitative,” Charlotte Miller, author of the Mobile Games whitepaper, said.

Juniper Research also forecasts that tablets will account for more than a third of mobile games revenues by 2016, with revenues from feature phones games halving over the same period.