@Utelake I moved your post over to this existing thread: Billed by Google - Switch to military plan
It looks like your account is currently upgraded through Google Play.
Joining or upgrading to a Pandora Premium Student or Military plan is currently not possible through third-party vendors (e.g., Apple or Google Play).
If you're interested in subscribing to Pandora Premium Military, check out the accepted solution to this thread for more info.
Hope this helps!