Then actually this wallet is good to use for so long period of time
This is wrong. Using any web wallet is a bad idea, especially for long periods of time. Just because they haven't hacked or scammed
yet, doesn't make them automatically trustworthy.
There are far too many things that can go wrong with letting someone else hold your coins for you, as you do with a web wallet or an exchange - scams, service hacks, account hacks, insolvency, shutdown, sudden KYC, etc. It is a much better option to run your own wallet and hold your coins yourself.