Because the DGLux module contains user data and your custom dashboards the upgrade procedure it a bit different than other modules.
Check the version you have installed on the Modules page inside your Mango Automation. Get the latest version of DGLux here: http://store.infiniteautomation.com/module/dglux
Make backup of /web/modules/dglux (very important as during the upgrade you will lose all your work inside DGLux and will restore it from this backup)
Download new module from http://store.infiniteautomation.com/module/dglux
Place new DGLux zip in /web/modules
Copy your files from the /dgml folder of your backup and any graphics you may have added to the /packs folder or any .pwm files you may have added or updated in the dglux/modules folder
5a. Copy License file is in /dglux/core
5b. In license file is a product id
5c. Copy this and past it into the "productId=" in /web/modules/dglux/classes/dglux.properties
Restart Mango and your DGLux module will be upgraded and the License will remain active.