Trust
Take it with you. Or take it down.
Both directions matter. An archive you cannot leave is not yours.
Export
Export is meant to return your memories in a form you can keep and read without Memora.
An export contains your memories and the context attached to them, in a form you can open without Memora.
Delete
Deleting means deleted, not hidden. That applies to a single memory, to a source's contribution, and to an entire account.
Deleted memories are removed from live systems immediately and fall out of backups as those rotate.