We need to purchase or extend this software to use this software in our other projects or subsidaries

Hello there, @humayun3871!

There are several functions you can utilize in organising your subsidiaries. First, the Class or Location tracking and the Project feature. You can read through the following articles below to learn more:

• Get started with class tracking in QuickBooks Online
• Set up and use location tracking
• Set up and create projects in QuickBooks Online

Lastly, here are articles you read for ideas to help manage your account and related tasks: Help Articles for QuickBooks Online.

If there's anything else that I can help you with, let me know int he comments. I'll be here to lend a hand.