Do I pay per learner?

Subscriptions are per learner, per grade. So you would need a paying subscription for each learner you would like to sign up. This is to ensure that they can each access the relevant content for their grade and receive results for their individual work. This also allows you to monitor each learner individually.

If you feel ready to sign up to WorksheetCloud, you can get started here: http://www.worksheetcloud.com/sign-up/