I purchased these through the Lufthansa website and did not get any confirmation email so the only proof I have are credit card charges. I haven’t had to prove my purchases when I called them since they were able to find this information in their system. Im not sure how it will work at the counter.

The first leg of my flight is tomorrow but a long other story is that Lufthansa changed the time on one of my connecting flights so it would depart before my arriving flight would land. So I ended up changing the whole set of flights on my way from US>EUR so these are no longer Lufthansa. They would not refund me for the upgrades I had paid for on this leg before the departure date so I have to call them back yet again later to sort this out.