You should always keep your plugins and WordPress versions up-to-date to avoid any security vulnerability. However there maybe times when you need stop a plugin from updating, for example when you have modified it. The following code snippet will stop any update notifications for a specific plugin.
You have to put the above code at the end of your
* Don’t forget to change line 5 with the appropriate plugin name / path (eg. akismet/akismet.php for akistmet plugin).