Yes, there is no time limit which you may have an account with balance 0.
Also there is no fees for maintaining your MT4 account.
With FBS, you can have up to 5 live accounts for each account type and unlimited number of Demo trading account.
Expiration date of MT4 and MT5 accounts
Both live and demo accounts of FBS will expire (be archived) when 90 days pass with no activity in the account.
Demo accounts will be expired and closed, you won’t be able to retrieve it.
You can open new demo account as many as you want.
Live accounts will be archived, but you can reactivate it from the client portal.
For more information about expiration dates of FBS MT4 and MT5, and How to retrieve them, please go to another FAQ here.