QuickApps for SharePoint use the SharePoint Central Administration (CA) to manage the license, so that the license will be saved on the CA server. 

When loading a page that contains a QuickApps for SharePoint webpart, it will try to read the license information from the CA server, and then check whether the license is valid.

1. If the license is valid, it will save it to the page cache, so that it can read the license info from the cache directly  next time.

2. If something bad happens during this process, it will show this error message:

Your evaluation period has expired or your license is for different version of QuickApps for SharePoint. Please contact Dell Software (http://software.dell.com/) to obtain a valid license.