No, if you've purchased the one-time in-app purchase called "Unlock all features" (offered in app versions 2.1 and lower), we've promised you lifetime access to all new features.
Simply sign up for an account, after which the app should prompt you to restore your previous purchase. After this all features should be unlocked.
If the app didn't automatically prompt you, go to "My Account" by tapping the icon in the top right of the main menu. Then tap on "Upgrade to Premium", and press the "Restore previous purchase" button.