Cubase 10 Pro Crossgrade from Logic Pro X


I want to crossgrade from Logic Pro X to Cubase 10 Pro. Unfortunately I do not have the receipt of purchase (from 2012 or 2013), and Logic Pro X does not come with any serial number. I don’t have any logic pro box as it was purchased through the Apple App Store as a software download.
I have been to the local reseller twice (in Denmark) but they do not know how to proceed with the crossgrade in this regard and referred me to ask Steinberg directly.

What kind of proof would I need to qualify for this crossgrade?
Would a screenshot of the Apple App Store be sufficient showing for instance my iCloud account and the apps I own?
I have also downloaded Store Transaction History through which contains all transactions made with my App Store account.

I have the same problem right now. Did you find a solution?

I went to the store with screenshots of my purchase history and whatever I could find. I never got a proper answer from Steinberg on who has to authorize the Crossgrade copy, but it seems that it’s in the hands of the reseller to verify that you own the product you are cross-grading from.

I don’t remember exactly how I found the purchase history, but I believe it was through the App Store on Mac. Or through iTunes (which I believe no longer exists on the newest MacOS).

The box that I purchased (Cubase 10 Cross-grade) contained an activate code which I could use without any further verification process.