Spin evolution of GJ 1148 b with adopted R = 9.44 R_⊕, k₂ = 0.341,and Q = 18 000 due to star–planet tides (left) and tidal evolution of Mars-like (m = 0.107 M_⊕, R = 0.53 R_⊕, k₂ = 0.14, Q = 140) and Titan-like (m = 0.0225 M_⊕, R = 0.404 R_⊕, k₂ = 0.589, Q = 58.9) exomoons due to exomoon–planet tides (right). The initial rotational period of GJ 1148 is P_rot = 11 h (consistent with Saturn), while of exomoons it is P_rot = 24 h (consistent with Mars). Asymptotic rotation at 2∕3 of the orbitalperiod is reached for GJ 1148 b after ~850 Myr. The Saturn-like planet therefore reaches P_rot = 27.5 d, which leads to strong orbital decay of the N-body stable exomoon orbits due to tides with the planet. The initial exomoon orbits are adopted from those that survived the N-body stability test in Sect. 5.3.1 (see also Fig. 10).