So my question is: Which license key do I need to activate the trial. Since we do not want volume licenses, I did a little research, and found out that some people that need to change the path of the install location, installed the trial version of office which comes with the msi Installer, and then activated it. After hours with the Microsoft support, we found out that the msi Installer for Office 2013 we need for this, is only shipped with volume licenses. So when we tried office 2013 and therefore simply bought an single 'Home and Business' license, we soon recognized that with the (Irony on) wonderful (Irony off) Click-to-Run Installer we can not achieve this.
Due to some third-party software, we have to install office in the 32 bit Version, but it must not be in a path with '(' or ')' in it (This is an issue with an oracle client, and we definitely can not change here).