If you find that TPE or TPT (or any other iOS app for that matter) appears to be stuck in an install or update cycle that never completes, here are some troubleshooting tips:
- Try shutting down and restarting your device and then retrying the update
- In the device Settings screen, under iTunes & App Stores, confirm that you're signed in correctly with the same account used to purchase the app you're trying to install or update.
- Try the troubleshooting tips that Apple suggest in their article here: If you can’t download or update apps on your iPhone or other Apple device
Unfortunately, this seems to be a relatively common issue that can affect almost any app - a web search will turn up a variety of other suggestions on handling the problem.