I have a freemium platform, that currently allows only social sign-up (twitter or instagram). We are now also offering paid services, and an option to upgrade your account.
There are two relevant flows we have:
1. Existing user which already signed up with social network - should we require an addition of password to the account?
2. New user that is not logged in and is signing up for a trial for the paid version - is it ok to let them signup through social network?