In this case, if you purchase Ridgeline 3.1, your Distributor have to open a case in Extreme's TAC (if you have PartnerWork service, but if you have direct service - you can open a case in eSuport yourself), and TAC have to give you free license for Ridgeline 4.
In case if you purchase Ridgeline 4.0 Base-50 then TAC have to give you install file.
Thank you!