When I try to search a PDF saved on my C drive, I get an error saying "your trial has expired", buy. But I purchased a pre-paid subsription in December

Hi roberte,

On checking the details for your account using the email address you are logged into the forums, you have subscription for adobe pdf pack as well as trial for acrobat.

Try following troubleshooting steps:

1- Download and run cleaner tool on the machine to uninstall Acrobat trial:Download Adobe Reader and Acrobat Cleaner Tool - Adobe Labs

2- Then download and install reader from here : Adobe Acrobat Reader DC Install for all versions 

Sign in with your adobe credentials and check.

For more info on pdf pack, refer: FAQ | Adobe PDF Pack

Let us know if you need any help.

Shivam