Alternative to the PowerShell global scope - powershell

Question

I am writing a function in PS that caches a password that a user provides. It does this by encrypting the password and saving it to disk, then saving the encryption password and key as a secure string in a global variable. This way the next time the function is called, it will have access to the key. After x minutes a job deletes the file from disk, and if the session is closed, the encryption key is lost.
having ran the PSScriptAnalyzer through my code it is (rightly) complaining about using a global variable. This is an issue because at some point I could very well want to push it to a repository, so I can't just ignore that error.
I also don't want to save the key to disk, as that wouldn't get cleaned up at the end of the PS session.
Is there a more suitable place I could store this data? (that will get wiped when the session closes)
ETA
I'm looking for an alternative to storing data in the global scope, that won't persist across PowerShell sessions. i.e. when I close the window the data is lost. I already have encrypted data on disk, I want to throw away the encryption key when the session ends.

Answer 1

You might want to keep the credentials inside the variable (perhaps a $script: scope one). I heve build a function for this a time ago.
function Set-Credentials
{
[CmdletBinding()]
Param(
[Parameter(Mandatory = $true,ValueFromPipeline = $true,Position = 0)][ValidateNotNull()][String]$UserName,
[Parameter(Mandatory = $false,ValueFromPipeline = $true,Position = 1)][ValidateNotNull()][String]$UserPassword
)
if (-not$UserPassword)
{
$Password = Read-Host -Prompt "Specify password for $UserName" -AsSecureString
}
else
{
$Password = (ConvertTo-SecureString -String $UserPassword -AsPlainText -Force)
}
$Credentials = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList #($UserName, $Password)
Write-Output -InputObject $Credentials
}