Every Fleep conversation has a conversation setting for message history, "Show previous messages to new members" (previously called "Disclose"). By default, this setting is disabled for new group conversations, 1:1s and monologues, and it is enabled for all team conversations.
This setting determines whether new members who join the conversation see the messages that have been posted before they joined.
If you are a Fleep for Business user and enable this setting for any Premium conversation where it was previously disabled, then message history will be disclosed to everyone up to the point when the conversation was created (or when the conversation was turned into a Premium conversation).
If you are a Basic (free) user or a Fleep for Business user and enable this setting for any regular, non-Premium conversation where it was previously disabled, then message history will be disclosed to everyone up to the point where you joined / have access to in the conversation.