DJ.Studio now has an offline mode, meaning you can use the software without an active internet connection.
After installing and authorizing the application on the internet for the first time, you should be able to launch the app without a connection.
There is no need to switch any options. Simply open DJ.Studio without being connected to the internet and it will run in offline mode.
Note, that any online features (YouTube mixing, 1001Tracklists etc) will not be available in offline mode.
Test Offline Mode
You can follow these steps to test if offline mode is working:
Open DJ.Studio
Disconnect your internet (turn the wifi off in your OS settings).
Check if DJ.Studio works still.