What are the Licensing, rules of usage around Adobe Creative Cloud Express?

Yes, commercial use of what you design in CCX should be ok, including for flyers or on social media. That's primarily what Creative Cloud Express is intended for.

The only factor would be the licensing terms of any stock assets you might use in your design.

Here's more information if you use Adobe Stock assets:

https://helpx.adobe.com/stock/help/usage-licensing.html

Hi there, 

Thank you for choosing our product. We are sharing a few links to learn more about CC Express. With your premium membership to Creative Cloud Express, you can access the entire royalty-free Adobe Stock photo collection*. Adobe Stock photo licenses vary from limited to standard. For complete license information, click here. You may visit the website to check all the features. Here is another link to learn more about this app. 

Please write us back if you have any questions. We will be happy to help.

Thanks

Manmeet