keep free version after upgrading to pro premium

Hi,
That is a great question.

The Pro version is an extension of the free version, it needs a base to stand on.
Without the free core you wont be able to use the Pro version.

It is like building a house, you need the foundation to place the roof on.

If you are a Pro user, and want ore information – please open a ticket through your profile in Elementor.com to Costumer Service.

I hope this helped.

For pro or commercial product support please contact the developer directly on their site. This includes any pre-sales topics as well.

As the developer is aware, commercial products are not supported in these forums. I am sure they will have no problem supporting you there.