I subscribed to Premium today from my Mac - but have been unable to login from iPhone or iPad apps. Is there a normal delay or is it me?
Please clarify - you can't log in through the iPhone/iPad at all or can you not use Premium features there?
In the first case, please make sure you always use not only the same login credentials, but also the same login method (Google or manual) across all devices.
In the second case, please log out and back in and the account will be recognized as Premium right-away, if it won't - delete and reinstall the Todoist app on your iPhone/iPad.