HELP!!! I just purchased MixMeister Express 7.5.7 on the Mac App Store & can't upgrade to 7.7?

So, how does this really work? I called tech support. Sent sales an email.

Do I have to pay for version 7.7?

I have the Apple App Store receipt with me. Do I post it here?

How do I get a serial number so I can register my product?
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