obscure LearnDash license key (no jQuery)

leland_learndash_obscure_license_key.php

<?php
/* 
 * Snippet provided as-is with no warranty and no support.
 * Not an ironclad way of preventing license key exposure. Note word "obscure."
 * Test on staging/development environment to ensure needs are met prior to applying to production
 * Inspired by https://gist.github.com/rali14/3407a1b3efe149cfa3f17caff8743eda
*/

function leland_learndash_obscure_license_key() {
	?>
	<script>
		function lelandLearnDashObscureLicenseKey() {
			const ldLicenseKeyInputs = document.querySelectorAll('input[name="nss_plugin_license_sfwd_lms"]');

			if ( ! ldLicenseKeyInputs ) {
				// Go away if no license keys detected
				return;
			}

			for ( const input of ldLicenseKeyInputs ) {
				// Obscuring of license key occurs here.
				// Do NOT submit license key form again otherwise a bunch of asterisks will be submitted instead of a valid license key
				input.value = '*********';
			}
			
		}

		lelandLearnDashObscureLicenseKey();
	</script>
	<?php
}
add_action( 'admin_footer', 'leland_learndash_obscure_license_key' );

Consider altering line 13 if ProPanel license is applicable...

const ldLicenseKeyInputs = document.querySelectorAll('input[name="nss_plugin_license_sfwd_lms"], input[name="nss_plugin_license_learndash_propanel"]');

Can't imagine how it could hurt to add that even if ProPanel is not active on the site although haven't tested yet.