@dominic_cuynen as you have discovered, EX2300 is a special case for both how licenses and VC are applied. For either case, license is required on each switch, not just 2 (master and backup RE). EFL is required on this one EX product (to-date) for VC and is required on all members.
For all other EX products, any licence is only required on 2 of the switches with a VC, equal to one on Master and one on Back-up RE.