First, create a file called license.txt in $HOME/intelephense/license.txt and paste in your license key. Save that file.
Note
Another option is to create a file called licence.txt directly in $HOME.
If you do this, you must name the file correctly (including the typo!)
Next we will want make sure we have intelephense installed on our host. There are numerous ways to do this. The most common is to use Mason but I opt to do a global install of the package with NPM.