Purchasing PRO/PRO+ gives you expanded access not only in the web account but also in the App, including offline access to your scores at any time and a mixer tool.
The list of PRO features can be found here.
PRO+ is a new tier of subscription linked to the Official Scores
These scores are licensed directly from many of the world’s largest print music publishers and are the same, official, arrangements that appear in printed form.
How to upgrade your PRO subscription to PRO+ read here
Keywords: benefits, subscription, PRO.