The location-based service flags up offers for O2's 22 million customers from nearby retailers participating in the scheme, including WH Smith and French Connection.
A heavyweight ad campaign for Priority Moments has been running for just over two weeks, perhaps helping to explain its bounce back into the top spot.
After Sky Go, there is a new entry at number three from Channel 4 in the shape of Fish Fight, an app themed around TV chef Hugh Fearnley-Whittingstall's campaign for sustainable fishing.
Co-branded by Selfridges, Fish Fight is a guide to buying, cooking and eating sustainable fish.
The chart is powered by analytics app developed by with non-commercial branded apps removed.