Teacher use for student mote response.

I had emailed MOTE to ask which version I needed as a teacher, so that I could ask for unlimited student responses. I was told the $59 version is what I needed. My students are receiving the message that they are have met their mote entry and will need to pay. If I would have known that my students were going to have to pay, I would not have paid for this version. I thought I was going to be able to add my students to my account, but I can not figure out how to do that if I am able to. Some insight and help would be perfect.