Definition of a "member"
A "member" in Lightpost, is any man, woman or child, under the oversight of the elders at your congregation, that belong in the church directory.
This is not to be confused with being a "member of the Lord's body", which is identified by the baptism status on each individual user.
Permissions
When someone is a member of your congregation in Lightpost, they have access to login to Lightpost and access your congregations' account; as long as they have an email address on file for their user account. (Or have setup alternate login options)
How to make someone a member
A member is "marked" as a member by being added to a Role that "indicates membership".
This flag on a Role can be set under the "General Settings" tab when editing a Role, and selecting the appropriate checkbox. Here's an example:

*These default Roles should have been setup for you when your account was created.
Recommendations
It is highly recommended to follow some best practices for this special flag on Roles.
- Only make one Role "indicate membership" (usually the "Member" role).
- Only make one Group "indicate visitors" (usually the "Visitors" group).
- There is no need to create a "Visitor role".