I got my Licence in July 2016 but my membership is renewed in October every year. Two separate subscriptions.
Level 3 you are licenced to do pretty much anything I think apart from Payroll and Self-Assessment Tax. I took Level 4 and to be honest I didn’t learn much there that I have used. I know some very accomplished bookkeepers running very successful practices who never went beyond Level 3.
Good luck with your new practice but allow plenty of time for your licence application to be approved. I suggest you start the process straight away.