You can use the Joomla! Updater to update all JEvents components, modules and plugins.
Although JEvents and it's addons can be installed on an unlimited number of Domains with just one membership, we have restricted the usage of the Joomla! updater to 10 domains per account. We beleive this is a fair usage given the cost of our memberships.
So you can have 10 sites with a one click updates, noting that you need to generate a Download ID for each domain. To create download Ids you should make sure you are logged in and then click the user icon at the top of this page and follow the instructions.
Note, if your membership is expired then updates for club addons will stop.