Why any companies offer a free ERP ( Enterprise resource planning ) software to user ? What is the Reason  Behiend this 

As with all software industries, there are developers who see the potential for quicker and more flexible technological development; 

by offering their software as open-source, lots of developers can pitch in and make large improvements and advance the software to become more encompassing.

Companies that offer their software as a free tier typically want your business to grow with their software, and as your needs grow you will upgrade to their paid offerings. 

Free ERP systems can come with limitations on user numbers or number of transactions in a system, or even limitations on features themselves.

 As a company grows and sees the value with ERP, you will likely want to expand your features and functionality to fully support all your business functions. 

This may mean buying extra modules that can improve your software's abilities, such as adding an ERP finance module.