In case the license should not be renewed, this option can be turned off, like mentioned below :
1. Login at myNomadesk.com with your Group Manager account and click Manage.
2. Go to Billing -> License Overview and click the eye icon of the license that you want to stop from autorenewing.
3. Click the Auto Renew option. Red = turned off. The license can still be used untill the end date, or turned back on to auto renewal. Don't forget to click Save.