PX-Essential - ERROR: License is expired, PX-Central server not reachable

Hey,
Thank you for reaching out, we have a fix for this in the latest release for PX-Essentials, i.e. 2.5.5
If you can share your spec with us, I can verify which version you are trying to install and help guide you to update it.
Also, if you could share more details about your architecture, it will help us debug this issue quickly.
Thanks,
Tapas Sharma