Gadget owners will spend $75 billion (£48.57 billion) a year on apps by 2017 a report has claimed.
The figures comes from Juniper Research and follow a study into the future of apps stores.
According to Juniper, the total amount spent on apps by owners of smartphones, tablets, smartwatches and other devices will be $75 billion within five years.
It also found that around three quarters of that figure will be the result of in-app purchases.
Read more: Government to investigate F2P games
The remaining 25 per cent will come from the cost of apps at the time of download.
According to Juniper, it believes that more and more developers will find a way to monitise their customers. This will be done through a combination of advertising and in-app purchases.
The report says that games will account for the biggest slice of revenues in 2017. Nearly one third of all revenues will be spent on gaming.
It also believes that tablets will continue to grow their share of the app revenues over the next five years.
By 2017, Juniper anticipates that tablet apps will be generating $26.6 billion (£17.23 billion) in revenue. That compares with the $7.8 billion (£5 billion) expected this year.