$software = "Microsoft .NET Core Runtime - 3.1.0 (x64)";
$installed = (Get-ItemProperty HKLM:SoftwareMicrosoftWindowsCurrentVersionUninstall* | Where { $_.DisplayName -eq $software }) -ne $null
If(-Not $installed) {
Write-Host "'$software' is NOT installed.";
} else {
Write-Host "'$software' is installed."
}