In case your license expires (trial) and pop-up window starts appearing you can disable MDT to keep working with your Eclipse.
There are two ways to accomplish that:
First:
1. Switch your current perspective to one not related to MDT (i.e. Resource)
2. Close all views and windows related to MDT.
3. Restart Eclipse (File-->Restart)
Second:
1. Uninstall MDT plug-in