Bitcoin is a digital currency that circulates freely, without any control or supervision from banks, governments, or anyone else. In contrast, bitcoin relies solely on cryptography and software between computers.
what if the government closes or does not allow the exchange of Bitcoin or cryptocurrencies with the official currency in each country?

Then exchange it in the country that still allowing it, closing bitcoin exchange wont stop us at all, there's must be payment channel that accept bitcoin since its precious and valuable.