Have you received the automatic email with the license key file? If not please check your junk email folder.
From this email save the attachment "FlowHeaterDesigner.lic" to a local folder on your hard drive.
To activate, go to the menu option in the Designer "?->License" and click the button "Read license file"; selecting the saved attachment. The freeware version switch now to the full version you have paid for. Thanks.
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