The first thing I need to say, right off the bat: Chinese users will not buy your software. Period. That does not mean that there is no money to be made, it simply means that they will not pay for your software license.

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

Prevents you from data breaches and liability risks
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Selling your software in China « Successful Software

Rails Long Term Support