I’m aware of the fact that one can use the Unity 5 Pro license on older versions (Unity 2, 3, 4) and still get the pro features. What I don’t know is: do I still get the pro features on older versions of Unity if I choose the subscription payment method ($75 per month)?
A Unity 5 Professional subscription
gives access to the latest version of
Unity 5 Professional, including
Pro-only benefits, within the
subscription period, as well as all
previous versions. Any new releases
occurring during your subscription
plan are automatically included at no
additional cost.
Short answer, Yes you will.