When you run a CPC based push notifications campaign, please pay attention that you may get some late reaching clicks. The number of clicks depends on the amount of received traffic.
TTL (or time to live) of our push notfications is 24 hours - this is the maximum time limit for getting clicks.
In order to prevent traffic overflow, we recommend setting campaign budget limit lower than desired spending. We are currently working on an algorithm that will avoid this problem in the future.