You only have to republish the files again with a licensed version,
Welcome to Adobe Forums. Please accept my apologies for the inconvenience.
This is a phenomenon which happens with trial versions of Captivate. If you have a project created in a trial then it is set to expire on the expiration date of that trial. However, if you have a licensed version of Captivate then you have to just open the ".CPTX" file created using the trial in the licensed version and then go to Edit > Preferences > Project > Start and End look for Project Expiry, uncheck that, save you project and publish it again.
If you do not have a licensed version then you can get a Captivate subscription for a month.
Hope this helps!
Thanks for the answers!
In my PowerPoint I have the files saved as .swf and I cannot find the original captivate files. Is there any way to import the .swf files into captivate and then modify the expiration date?
Unfortunately no. SWF is the output format, not the editable source.
If you cannot locate the original source files you may have to just recreate them from scratch.
Yes as the SWF is the published output so you would not be able to edit it.
You may have to edit the source files and republished them.