Free for a day Apps - legal for use in Apple Configurator?
Most software has an EULA | End User License Agreement associated with it — which is essentially a contract between the licensor and purchaser, that defines how the established purchaser can use the software along with the liability of the licensor.
EULA's are deployed in many different ways; often you might never see or know where to look for one within an application and/or on the developers website. Each application has it's own agreement(s), rules, and fine print. For every app you have it's likely to have an agreement that is completely different from another.
I had very tough time finding the EULA for Comic Life, since the website contained nothing that I could find. I eventually found it in the application under Window &gt; Software License Agreement. I downloaded the trial version, so the eula associated with my version likely differs from yours. I'll spare you the entire agreement, since it's roughly 2383 words long.
Here's Section (B):

B. Comic Life Single User License. This License allows you to install
and use the plasq Software (whether trial or full version) on all your
personal computers. These are computers that are exclusively used by
you alone.

So for this version you would need to be the only person in your classroom using the application or the computers, which seems a bit comical really :D