When a webspace expires it will be deleted, meaning you will no longer be able to administer the domain for the webspace.
If you do not wish to keep the webspace for a domain, but still want to keep administration and renewal of the domain, you can downgrade the webspace to a DNS Service before it expires.
This can be done from the Administration menu, found in our control panel by choosing "Change product".
Article from the support category: Domain & DNS