Can I use this application for commercial use?  

Hi @dane,
Currently we are still in BETA. Please feel free to use the current spacedesk BETA software for corporate business use and private use until it expire (August 2021 at the earliest).
After we come out of BETA, there will probably still be a free version with a limited feature set for business and private use.
The pay version will contain the full feature set. It will probably range around € 10,- per client.
Payable through the App-Stores (iOS, Android and Windows).

Posted by: @dane

I`m finding solution to use the dual monitor when users work from home. and this application seems perfect solution.

But I`m not sure if our users can use this without license purchasing. and I couldn't planter tomato find proper answer about this.

so my question is - is <a style="color: #333333; text-decoration: underline;" href=" removed link " target="true">here

The easiest way to do this is to right-click on the desktop and select 'Display settings. ' Scroll to the bottom and you will see the heading 'Multiple displays' and the option to either extend or duplicate your display.