Hello Deidrer,
We apologize for the inconvenience caused, as per the description you are not able to use the Adobe ExportPDF service with Acrobat Pro trial once the trial got ended, Is that correct?
Adobe ExportPDF service is an online service and it can be accessed through a browser and with the free desktop version of Adobe Reader DC.
If you will try to use the services through Acrobat Pro DC once the trial is over, you will get error messages.
Please use the service through the URL https://cloud.acrobat.com/exportpdf with your Adobe ID and password on a browser like Chrome, or Firefox, or Safari.
You can also download and install Adobe Reader DC, and use the service of Adobe ExportPDF, just "sign-in" with your current Adobe ID and password. Download Reader DC from https://get.adobe.com/reader/enterprise/
For troubleshooting, you can refer to Troubleshooting Create PDF, Export PDF, Adobe Send, Fill & Sign … services(PDFPack or Document Cloud Services).
Please uninstall Acrobat Pro from the computer, reboot the machine and install Adobe Reader.
Feel free to update this discussion for any further assistance.
Regards,
Anand Sri.