How can create multiple companies under one subscription ? and How much will cost me ?

The "how" is outlined here https://quickbooks.intuit.com/community/Help-Articles/Create-or-add-another-company/td-p/185919

The cost will be the going rate for each version you add. You can mix and match, they do not all have to be same version. 

@waleed-ghaly 

If they all are under one legal entity with different DBAs, you can use "Class" in one subscription. Only in Plus 

...or Advanced

Advanced is not worth suggesting, unless you have 25 accounting staff, which means no one

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@Malcolm Ziman wrote:

Advanced is not worth suggesting, unless you have 25 accounting staff, which means no one

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Advanced has nothing to do with accounting staff. It has more to do with sales staff or mechanics in a garage setting. Accountant users are not restricted to only 5 staffers. What is the OP has 71 DBA's to keep track of by Class - they would need Advanced. What if they have enough assets that  they exceed 250 in their chart of accounts - they would need Advanced

….or Desktop

The chances of anyone having more than 40 DBAs are the same as an asteroid hitting earth today, and if anyone has more than 250 active accounts, they are doing something wrong.

And no one would give a mechanic access to their books, with the pathetic user access controls that QBO has, even the so-called enhanced ones that Advanced offers (I have looked at them - nothing much there - cobbled together some small features quickly to call it "enhanced")