Microsoft Publisher update

Hi there
Recently bought computer with windows 8.
Have been using the Microsoft publisher and saved/back up my work.

After a month when I now open publisher it displays
"To keep using publisher without interruption. Choose an option etc"

It is asking me to now pay for publisher.
Do I need to do this ? Is this just an upgrade or it actually replaces the existing publisher?
Will I lose my existing files, not be able to print out my saved work?

Can I just keep using publisher after closing the interruption window , every time I open publisher ?
Don't want to open it up in the future to find I cannot print out my existing work saved in publisher.

Many thanks