Why do you want to export the host?
If you only want to upgrade the edition from free to enterprise then you can do this with your complete instance.
What you can do to “export” your hosts is inside the filesystem ~/etc/check_mk/conf.d/wato/ you will find your folder structure from inside your web configuration. If you want you can copy a complete folder with all the hosts inside to a new instance. Only pay attention to the owner and group of the copied files that they match the target site.
One other way to get hosts “exported” is to make a livestatus query who prints all hosts with some wanted attributes like alias and IP.