If you purchased Office 365 prior to October 2014 you may have an older P (Small Business) or M (Mid-sized Business) plan. Once the new Business plans (Business, Business Essentials and Business Premium) where announced pots October 2014, you could no longer purchase the P or M plan new (you could add to existing plans but could no longer buy them new).
Existing P and M plan users then had a maximum of 12 months to upgrade from these plans to new plans. If they hadn’t done so by 1 October 2015 then they would automatically be upgraded to the equivalent plan.
I details all of this in a prior blog post:
and from this blog post:
The follow table outlined the automatic upgrade routes:
Microsoft has recent announced further guidance around this automatic upgrade process which you can find here:
which basically says:
After October 1, 2015, you will need to select one of the new plans at your next renewal date. These new plans are very similar but not identical to your current plan.
The biggest change I see is that existing M plans have RDS right but after October 1, 2015 they will be migrated to Business Premium plans which DON’T have RDS rights.
If you are yet to move from the old plans ensure you check out this new guidance website from Microsoft to understand what will happen to your tenant after 1 October 2015 and the changes in functionality that will mean.