I am also thinking about subscribing as an instructor because 1 GB of memory is not sufficient to install rstan or TensorFlow (Stan on Rstudio cloud not working, Installation of tensorflow terminated on RStudio Cloud - #9 by wlandau).
All my projects live in "Your Workspace" and are public. When a student runs one (either in a temporary copy or saved copy) who pays for the hours? Is this different between the free and instructor plans?