The general Microsoft mainstream support for SharePoint 2013 will end by April 10, 2018. But don’t panic! Your SharePoint farm will still be working. It actually keeps receiving security updates. However, Microsoft no longer distributes non-security updates or accepts requests for new features. But all knowledge base articles and product-specific resources will remain online, although the content is not maintained anymore.
If your farm is still running on SharePoint 2013 you should consider an upgrade to SharePoint Server 2016 or SharePoint Online. But at least you have to upgrade your SharePoint servers to the April 2017 cumulative update or later to get support from Microsoft after April 10th, 2018.