If the Planboard for iOS app is constantly asking you to log in every time you open it (we apologize because we know how frustrating that is!), just follow these steps:
1) Tap on the menu button in the top left
2) Tap on 'About'
3) Tap on 'Clear Local Data'
4) Tap Clear
What this does is it clears the app's locally stored data (which in this case is a secret token that the app uses so that you don't have to re log in every single time).
5) Quit the app, and then re log-in
Now, the next time you open the app, it will not ask you to log in again as it will save your credentials. Phew!