Microsoft has started to display a warning to users running Windows 10 1803, otherwise known as the April 2018 Update, that states the version is nearing end of support and that they should update to the latest version of Windows. Windows 10 will eventually force users to upgrade to latest version in order for Windows to be properly secured. Windows will no longer receive security updates and will be vulnerable to any new security threats that are discovered. Users will get an extra year of support, with their end of service being November 10th, 2020.
Source: https://www.bleepingcomputer.com/news/microsoft/windows-10-1803-users-warned-to-update-before-end-of-support/