Microsoft SharePoint Server 2013 will be going end-of-life on the 11th of April 2023. Once the product goes end-of-life, it will no longer receive security updates, patches, and technical support from Microsoft. Make sure that all of your on-premise installations are on SharePoint Server 2016 or higher.
Once SharePoint Server 2013 goes end of life, there will be 3 supported on-premise versions remaining: 2016, 2019 & Subscription Edition.
If you have current Software Assurance cover on your SharePoint Server 2013 licenses then you are entitled to upgrade them to SharePoint Server 2016 or 2019.
As an alternative to SharePoint Server 2016 or 2019 you might consider migrating to the latest SharePoint Server Subscription Edition or SharePoint On-Line. The latter can be purchased as a stand-alone plan or included within a Microsoft 365 plan.
Note that you will need Software Assurance (SA) on existing SharePoint Server licenses to be able to access the subscription license.
You might find the following links helpful:-
sharepoint 2013 end of support – Search (bing.com)
What is SharePoint – Overview of features (microsoft.com)
SharePoint updates – Office release notes | Microsoft Learn
If you need independent advice with your Microsoft Licensing, Software Assurance & Subscriptions then please contact The SAM Club at [email protected]