Installing Draftsight in a highschool

Hello,

I am a teacher of CAD in a highschool and I wanted to teach my pupils Draftsight in the classroom. I wanted to install Draftsight in each computer (20 overall). The question is: Do we need to purchase the premium license for educators or it is enough installing the standalone vesion in each computer. I would really prefer to install the standalone version because of the tight budget we have but I am not sure if it is possible.

Thank you very much in advandce and I look forward to your answer. 

Ruben