'you' as an individual can't have a Developer Enterprise Program account, unless 'you' are a company.
A company/LLC can have both ADP & ADEP (timing isn't a factor), in which case the credentials/apple IDs for both must be unique/not the same so the backend knows which account is being used when logging in. Apple IDs are cheap, so there is no burden working with two other than needing to keep track which is being used at a given point in time.
There is no 'cancel' later...accounts expire.
And so we're on the same page, it is 'program', not plan. See the 'Programs' link above for details.
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Tags: Programs