Copyright vs Licence

Hi All,

I have been playing around with the pg_auto_failover extension by citus and
have really enjoyed playing chaos with it.
citusdata/pg_auto_failover: Postgres extension and service for automated
failover and high-availability (github.com)
<https://github.com/citusdata/pg_auto_failover>

Now I see this at the bottom of this extension.
This may be a stupid question, but i ask coz i have worked with OSS that
been marked EOL or dead.
Some software have started asking for fee (like oracle for supported java)
Some software which were completely open sourced for unlimited usage (like
sensu) now have a new version which has limited/capped free usage.
Or the Google vs Oracle case.

I know I can make a city of postgresql clusters of various sharded
architectures, and it will still be free and postgresql is not responsible
for any damage etc i understand, but can the extensions later charge on
usage model.

*Copyright (c) Microsoft Corporation. All rights reserved.This project is
licensed under the PostgreSQL License, see LICENSE file for details.*
I have a lame query (but i have a concern wrt how oracle acquired products
licenses changed)

What is the role of copyright in a license. (I am not sure if i am even
framing the question correctly, but let me know if i am not).
Can I be charged for whatever reasons in the future for using this
extension.

--
Thanks,
Vijay
Mumbai, India