How to check whether the latest version of a Mage2.PRO extension is installed?

Hi, where can i check if I have the latest version of the extension installed in my Magento 2.1.5 ?
Is there any file or composer command to verify this?

You can check it with the composer update <the extension's package> command.
If there is nothing to update, then Composer will say it.
See the official composer update documentation.

See also: