Once you buy the latest version of Website Builder, you'll want to move your v6 content to your new v7 Website. The v6 content will not be accessible after you publish the new Website.
Depending on your Website's size, this manual process can take a while. You may want to check out Options to migrate my website.
No need to spend a lot of time creating perfect pages — the goal is to move your v6 content over to the new Website as simply as possible. You can rename and polish your v7 pages later on if you like.