As I understand it....
1. You purchased a suite and/or all the titles.
(you own the rights to use those versions forever!)
2. If you go for the subscription plan you will gain access and upgrades to everything else for the duration of your subscription and/or until you decide to stop the subscription.
At which time you can go back to what you actually purchased. (but) everything that you had edited and/or created might not be functional for editing due to the fact that your created them with a newer version.
You won't have access to the latest and greatest versions, but you'll still have ownership and rights to the products you purchased.