T      - STAR Order's auto-renewal lifetime
    end    - STAR Order's auto-renewal end-date
    nrd[i] - nominal renewal date of the i-th STAR certificate


                 .- T -.   .- T -.   .- T -.   .__.
                /       \ /       \ /       \ /  end
    -----------o---------o---------o---------o----X-------> t
              nrd[0]    nrd[1]    nrd[2]    nrd[3]