Powershell Script setting WMI CIMV2 Permissions

I am currently trying do change up a script so that I can put it into a GPO. The Script itself works but I want to do a "if else" around it.

The Script is found here: https://gist.github.com/exchange12rocks/950aa29f66e6369d2c02fa8583bb3a75

The goal was to check if a registry key exists and if not, create it and set it to 1. So that way the Script only ever runs once.

I did the if else like this:

$isRegKeySet = Get-ItemProperty -Path 'HKLM:\SYSTEM\PRTGScript' -Name hasScriptRun -ErrorAction SilentlyContinue | Select-Object -ExpandProperty hasScriptRun

    If (1 -eq $isRegKeySet) {

        exit
    
    } Else { The Script from GitHub }

The Part that creates the Key is this:

Set-Location HKLM:

New-Item -Path .\System -Name PRTGScript

Pop-Location

Set-ItemProperty -Path "HKLM:\System\PRTGScript" -Name "hasScriptRun" -Value 1
}

I am not sure where to put these two parts so the script will work. I'm not a Powershell pro unfortunately.

My Script is this:

# Copyright (c) Microsoft Corporation.  All rights reserved. 
# For personal use only.  Provided AS IS and WITH ALL FAULTS.
 
# Set-WmiNamespaceSecurity.ps1
# Example: Set-WmiNamespaceSecurity root/cimv2 add steve Enable,RemoteAccess

Param ( [parameter(Mandatory=$true,Position=0)][string] $namespace,
[parameter(Mandatory=$true,Position=1)][string] $operation,
[parameter(Mandatory=$true,Position=2)][string] $account,
[parameter(Position=3)][string[]] $permissions = $null,
[bool] $allowInherit = $false,
[bool] $deny = $false,
[string] $computerName = ".",
[System.Management.Automation.PSCredential] $credential = $null)

Process {
    $ErrorActionPreference = "Stop"
 
    Function Get-AccessMaskFromPermission($permissions) {
        $WBEM_ENABLE            = 1
                $WBEM_METHOD_EXECUTE = 2
                $WBEM_FULL_WRITE_REP   = 4
                $WBEM_PARTIAL_WRITE_REP              = 8
                $WBEM_WRITE_PROVIDER   = 0x10
                $WBEM_REMOTE_ACCESS    = 0x20
                $WBEM_RIGHT_SUBSCRIBE = 0x40
                $WBEM_RIGHT_PUBLISH      = 0x80
        $READ_CONTROL = 0x20000
        $WRITE_DAC = 0x40000
       
        $WBEM_RIGHTS_FLAGS = $WBEM_ENABLE,$WBEM_METHOD_EXECUTE,$WBEM_FULL_WRITE_REP,`
            $WBEM_PARTIAL_WRITE_REP,$WBEM_WRITE_PROVIDER,$WBEM_REMOTE_ACCESS,`
            $READ_CONTROL,$WRITE_DAC
        $WBEM_RIGHTS_STRINGS = "Enable","MethodExecute","FullWrite","PartialWrite",`
            "ProviderWrite","RemoteAccess","ReadSecurity","WriteSecurity"
 
        $permissionTable = @{}
 
        for ($i = 0; $i -lt $WBEM_RIGHTS_FLAGS.Length; $i++) {
            $permissionTable.Add($WBEM_RIGHTS_STRINGS[$i].ToLower(), $WBEM_RIGHTS_FLAGS[$i])
        }
       
        $accessMask = 0
 
        foreach ($permission in $permissions) {
            if (-not $permissionTable.ContainsKey($permission.ToLower())) {
                throw "Unknown permission: $permission`nValid permissions: $($permissionTable.Keys)"
            }
            $accessMask += $permissionTable[$permission.ToLower()]
        }
       
        $accessMask
    }
 
    $isRegKeySet = Get-ItemProperty -Path 'HKLM:\SYSTEM\PRTGScript' -Name hasScriptRun -ErrorAction SilentlyContinue | Select-Object -ExpandProperty hasScriptRun

    If (1 -eq $isRegKeySet) {

        exit
    
    } Else {   
        
    if ($PSBoundParameters.ContainsKey("Credential")) {
        $remoteparams = @{ComputerName=$computer;Credential=$credential}
    } else {
        $remoteparams = @{ComputerName=$computerName}
    }
       
    $invokeparams = @{Namespace=$namespace;Path="__systemsecurity=@"} + $remoteParams
 
    $output = Invoke-WmiMethod @invokeparams -Name GetSecurityDescriptor
    if ($output.ReturnValue -ne 0) {
        throw "GetSecurityDescriptor failed: $($output.ReturnValue)"
    }
 
    $acl = $output.Descriptor
    $OBJECT_INHERIT_ACE_FLAG = 0x1
    $CONTAINER_INHERIT_ACE_FLAG = 0x2
 
    $computerName = (Get-WmiObject @remoteparams Win32_ComputerSystem).Name
   
    if ($account.Contains('\')) {
        $domainaccount = $account.Split('\')
        $domain = $domainaccount[0]
        if (($domain -eq ".") -or ($domain -eq "BUILTIN")) {
            $domain = $computerName
        }
        $accountname = $domainaccount[1]
    } elseif ($account.Contains('@')) {
        $domainaccount = $account.Split('@')
        $domain = $domainaccount[1].Split('.')[0]
        $accountname = $domainaccount[0]
    } else {
        $domain = $computerName
        $accountname = $account
    }
 
    $getparams = @{Class="Win32_Account";Filter="Domain='$domain' and Name='$accountname'"}
 
    $win32account = Get-WmiObject @getparams
 
    if ($win32account -eq $null) {
        throw "Account was not found: $account"
    }
 
    switch ($operation) {
        "add" {
            if ($permissions -eq $null) {
                throw "-Permissions must be specified for an add operation"
            }
            $accessMask = Get-AccessMaskFromPermission($permissions)
   
            $ace = (New-Object System.Management.ManagementClass("win32_Ace")).CreateInstance()
            $ace.AccessMask = $accessMask
            if ($allowInherit) {
                $ace.AceFlags = $OBJECT_INHERIT_ACE_FLAG + $CONTAINER_INHERIT_ACE_FLAG
            } else {
                $ace.AceFlags = 0
            }
                       
            $trustee = (New-Object System.Management.ManagementClass("win32_Trustee")).CreateInstance()
            $trustee.SidString = $win32account.Sid
            $ace.Trustee = $trustee
           
            $ACCESS_ALLOWED_ACE_TYPE = 0x0
            $ACCESS_DENIED_ACE_TYPE = 0x1
 
            if ($deny) {
                $ace.AceType = $ACCESS_DENIED_ACE_TYPE
            } else {
                $ace.AceType = $ACCESS_ALLOWED_ACE_TYPE
            }
 
            $acl.DACL += $ace.psobject.immediateBaseObject
        }
       
        "delete" {
            if ($permissions -ne $null) {
                throw "Permissions cannot be specified for a delete operation"
            }
       
            [System.Management.ManagementBaseObject[]]$newDACL = @()
            foreach ($ace in $acl.DACL) {
                if ($ace.Trustee.SidString -ne $win32account.Sid) {
                    $newDACL += $ace.psobject.immediateBaseObject
                }
            }
 
            $acl.DACL = $newDACL.psobject.immediateBaseObject
        }
       
        default {
            throw "Unknown operation: $operation`nAllowed operations: add delete"
        }
    }
 
    $setparams = @{Name="SetSecurityDescriptor";ArgumentList=$acl.psobject.immediateBaseObject} + $invokeParams
 
    $output = Invoke-WmiMethod @setparams
    if ($output.ReturnValue -ne 0) {
        throw "SetSecurityDescriptor failed: $($output.ReturnValue)"
    }
}
Set-Location HKLM:

New-Item -Path .\System -Name PRTGScript

Pop-Location

Set-ItemProperty -Path "HKLM:\System\PRTGScript" -Name "hasScriptRun" -Value 1
}

Thanks for the Help.