We regularly get Support Requests from students that their License Key has expired.
You may find that they email about all sorts of things but the core is that the key has expired. For example, they try re-applying, they simply don't know what to do, and often, it expired some time ago and they have a course submission due tomorrow and it's urgent to get Lumion.

Note: USA students should get two automatic emails advising them that the License Key will expire soon.
Either they do nothing, choose to ignore, or they never receive them because they are using a different email address.
Students in regions where a Partner has issued the License Key rely on the Partner sending out reminders.
Reply with this key article:
Standard Macro replies are available to cover a few different situations, but may still require some editing to suit:
Note:
peterm 28 June 2021: There are some procedural aspects that we will try and evolve for this situation because there are possibly too many, but most of it relies on communication.