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Your license key was sent by e-mail when you originally purchased. Your license key can also be found in the Help menu of Macrium Reflect by selecting About Macrium Reflect...
Lost keys can also be retrieved here:http https://wwwmanage.macrium.com/account/myorders.aspx
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2. Remove your license key and uninstall Macrium Reflect:
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You can download installers and license keys by entering your email address here:http https://wwwmanage.macrium.com/account/myorders.aspx
You should create a new Windows PE rescue CD on your new hardware.