It's common for us who work with Sitecore having multiple Sitecore instances locally.
When the time comes that the license.xml expires and needs to be replaced, it's a bit of manual work to replace all the locations. There are PowerShell scripts to replace all at once but I wanted it to be even easier, so tried pointing all license.xml to one license.xml file using symlink which is supported by Windows.
Saving below scripts into a PowerShell(ps1) file and executing should replace all license.xml files under c:\inetpub\wwwroot to link to the license.xml defined in the scripts. You can change the 2 parameters as well if required.
Also make sure to run the script as an administrator and make sure the target license.xml is readable by all IIS apps.