Thank you for contacting us.
Regarding your concern, we would like to inform you that our themes are web-application which is built on the WordPress.org core.
It has been out before WordPress.com launched its Business plan. The WordPress.com platform is suitable for static or e-commerce site with very least logical code.
Therefore, it’s not the platform for web application as EngineThemes provided.
If you need to get started for free, you can try cloud platform hosting like Google Cloud or Amazon web service. (Try Bitnami WordPress).
Hope this could clarify your uncertainty.