Use your browser to view the System Management module. Normally (on the server machine) this can be found at http://localhost:3000
After clicking License → offline activation the following dialogue appears:
Fill in the License key from your voucher and press generate. An XML file downloads to your download folder. After downloading the XML, leave the browser window open.
Go to my.colorware.eu and login (You can do that on another computer if you use a thumbdrive or network access to transfer the XML file). If you do not have a my.colorware.eu account, make create one.
In the my.colorware.eu environment select offline activation from the menu:
Upload the XML file (generated by MeasureColor), this will let you download an activation XML.
After that, go back to the MeasureColor server and upload the XML (downloaded from my.colorware) to the server to finish the activation.