Morning Christine. Right- you can only purchase one Freelancer license. The others would need to be Non-Commercial or Commercial, as the case may be.
The FL doesn’t have to be used for a portfolio per se- though it shouldn’t be used for a client’s site.
The pricing overview page has the details:
The Freelancer is a special version of ExpressionEngine that small teams (3 employees or less) can use to build their online presence with. Please note the following about the Freelancer license:
The Freelancer license may not be used for client work.
Only a single Freelancer license is allowed per ExpressionEngine.com account.
It’s available exclusively to small teams of 3 employees or less.