I read this artcile (How to provide live updates for extensions in Joomla?) before some months but each company have to create a unique plugin to accomplish to offer live updates for (commercial) extensions. I think it's insane for every third-party developer to create a system plugin only for that reason. I'm developer but I'm webmaster too and I use some extensions too, but really I don't want to have a dosen of plugins installed on my backend, that's why I'm sharing this Universal Live Updater plugin.
It's free and always will be. You can use only one plugin for ALL of your extensions!
Many developers daily are creating and maintaining dozens of Joomla Extensions, most of them like me, we don't have added auto-update feature in our paid extensions (really), probably because the Joomla Update system event is too poor.
Most developers create a plugin per extension to able to accomplish the auto-update feature. Is not bad but it's not the best way. Why clients & developers have to maintain so many extensions for a single-simple task?
This plugin will handle ALL auto-update extensions (UNIVERSAL SULUTION), the only thing you have to do is to add some parameters to your update XML in "downloads" tags
If you had something like that
<downloadurl type="full" format="zip"><![CDATA[https://mysite.com/index.php?option=com_ars&view=release&id=12&format=raw]]></downloadurl>
replace it with
<downloadurl type="full" format="zip"><![CDATA[https://mysite.com/index.php?option=com_ars&view=release&id=12&format=raw&source=JExtUpdater&license=paid&type=component&extname=example]]></downloadurl>
The magic world is "=JExtUpdater"
For more advanced checks we added a new event (onUpdateBeforePackageDownload) is fired for any plugin type but also for Module & Component!
Read the documentation for more details. It's too easy! Actually does not require any extra coding for your extension!