Why are my forced to migrate to new version and lock my last job

If you click on your name in the top right under licenses it will tell you when your included updates expire.

Okay is there a way to save the site i already created with the recent upgrade to the last previous version? like a downgrade file, so I can get to used the site? am frustrated. if I knew my license have ended, I would have used previous version to design it.

No one is forcing you to do anything.
If your license expired, you can continue using the last version.
https://nicepage.com/User/app/downloads