Hi

Initially I would try Belarc Advisor and print out the pages with your Licence details on.

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  wmic path softwarelicensingservice get OA3xOriginalProductKey

  This may show your key if it’s stored in your BIOS or system registry.

• Alternatively, use PowerShell:

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  (Get-WmiObject -query ‘select * from SoftwareLicensingService’).OA3xOriginalProductKey

• Tools like ProduKey, Magical Jelly Bean Keyfinder, Belarc Advisor, or ShowKeyPlus can scan your installed system and recover the key quickly.

Also go back and ask the store what they installed and where is the original.

Do you have this link????

https://www.dell.com/support/product-details/en-us/product/inspiron-1564/drivers

The product key should be on a label under the battery.

Check old documentation, emails, or boxes for the product key.