Your nonprofit organization can have formal members or not, depending on how broadly you want to spread responsibilities and rights. In a membership nonprofit, voting members might appoint the board of directors, remove a director, change the bylaws, or dissolve the nonprofit. Certain services of the organization might be available only to the members, such as access to a retirement program or listing in a membership directory. By contrast, in a nonmembership nonprofit, the board of directors typically takes the above actions.
Whether to structure your nonprofit with members will depend on many factors, such as the size of your organization, its mission, and your appetite for complexity.