How many people can use one treehouse account?

My sister and I are learning to code and we obviously use 2 different computers.

so I wanted to know if it was okay to use one account for 2 people in the same house?

I read in Termination section (7).

"You may notify us of your wish to reduce the number of additional users attached to your account or to downgrade to a different package at any time at https://teamtreehouse.com/account/enrollment, but such reduction will not take effect until the end of your current commitment period (which may be either a yearly or a monthly period). You will not be entitled to a refund for any periodic fee already paid in respect of such users or enhanced package, in accordance with paragraph 4.2."

so would a family member count as someone who would need to be added to some sort of group?