If I have a Business Class account, can I invite nonpaid members to my team?

[Duane Berger]

I often collaborate with people who are not in my firm but would like to invite them onto certain boards.

If I have a Business account, can I invite people without paid accounts to my team?

[Michael Pryor · Accepted solution]

Yes. That’s called a Guest. 
If you add someone to one board (but don’t add them as a member of the team) then they are a single board guest and you don’t have to pay for them. 
if you add them to two or more boards, then they are a multi board guest and you’d pay for them.