If you started this file on the day you downloaded the ID trial,
Open the file
(Navigate to) Help
Hold down shift+ctrl and click About InDesign
It will give you all of the information pertinant to the file, including creation and save dates.
Has a month passed?
I did not think it had been a full month because when I opened it about an hour ago, it still gave me the option to continue the trial. Can it cut out mid-session? I only have about 30 minutes left on this project. Is there some way to get a temporary extension? (I know that is a farfetched question, but I'm in a pretty desperate situation.)
I'm betting that there is some other reason why you can't save or export PDF. I don't know if a trial will cut out mid-session, but if I were a marketroid at Adobe I'd be horrified if my trial would eat my potential buyer's work in that way.
It's a CC trial, right?
When you say you can't save or export a PDF, can you give us a tiny bit more detail? Like, what happens instead? Can you export an IDML? If you try to Save As, what happens?
Try a Save As
Create another document and move pages from the problem document to the new - attempt to save
Create a simple, one word document and try to Save or Export
I cannot answer to how the trials work.
I expect you have an acount - (most) current releases are subscription based - check your account status
Check the date stamps in your Program Folders pertinant to InDesign
Find the first InDesign file you made, what is the date history?
Wait, false alarm on the inability to export to PDF. I apologize. That capability is still allowed. It's also allowing me to physically print, as well. In the file menu, the only options that are unavailable are Save, Save As, Check In, Save A Copy, and Revert.
I believe there's a known issue where this is happening to some Mac users. The workaround is to export to .idml. open that and save as a new file.
This solved my problem! Thank you so much!