What will happened if we will close our business anf stop the subcription in qb. By any chance, we can still recover and get back on our account or download our files?

They will delete your account after 1 year you cancel it. Resubscribe your account for a month and you can keep your data for another year. Another option, export your data out to XLS.

https://transactionpro.grsm.io/qbo