Update Version For Magento 2 Extension

[vietnama10]

Hello, every body. I want to ask for the issue when we update version of the extension which we customized, i don't know, have magento 2 supported to keep the modification?
And if no supported, What we do to keep the modification? 
[- Help me  answer the questions, please. -]

[Pronko]

What version of the extension are you updating? Is this extension version or some Magento modules your extension relies on?

[vietnama10]

Thanks for reply. I would like to ask the general for all extensions, when we're update.