Can I associate a customised web address to the website created during the trial period?

When activating the trial version you will be asked to enter a name for your website which will also be displayed in the web address like so:
At any time however you will be able to buy the service and choose to add a customised web address like the following: costing you just € 10,00 a year on top of the cost of the selected package.
By purchasing a customised web address, you will also get 5 customised e-mail accounts and have the choice of buying more additional services for your website.