If you are looking for an app to keep up with and help you bill your time, consider OfficeTime. There is an app for your iOS device and Mac that can sync. There is a free version and a paid version that costs $7.99 that allows wireless syncing.
You can create invoices and view graphs to see how your time is spent.
The developer lists the features of the pro version as follows:
* Track your time from your home screen or any app with the OfficeTime widget.
* No monthly fees.
* Increase your billables
* Know if you’re on budget
* Improve your productivity by knowing where your time goes
* Easy, intuitive, flexible.
* Pay once. Get for both iPad and iPhone
* Work offline. No need for WiFi or cell connection.
* Export to Numbers, Excel and tab delimited.
* Get cross team reports on your Mac or PC (sold separately)
* Work with cross platform offices (sold separately): PC, Mac , iPhone, iPad
* Run multiple timers
* Rapidly switch tasks
* Time in the background
* Free Apple Watch version! Quickly start and stop timers and see where your day’s at.
The Mac version costs about $47. The developer advertises a 120 day refund policy. You can learn more about the app here.
This slightly dated video gives you some idea about the app.
iPad Notebook 