Maximum ENLR size R_ENLR, max as a function of BH mass M_BH for the CARS sample. A linear best-fit relation to the CARS data is shown as the red line with corresponding confidence area highlight as shaded area. The changing-look AGN Mrk 590 and Mrk 1018 are denoted by the colored diamond symbols and the local hyper-luminous QSOs 3C 273 from Husemann et al. (2019a) as a star symbol. The right axis shows the AGN life time t_AGN in blue colors. Taking into account the effect of inclination and random sampling of AGN during their life time, our inferred AGN life time relation from MCMC sampling is shown as the blue line. An independent measurement of the AGN life time based on the He II proximity zones around z ∼ 3 QSOs from Khrykin et al. (2021) is shown as a blue point with uncertainties.