How do I upgrade from zorin 17.3 to 18?

[Aravisian]

Closed as duplicate of:

Updating from Zorin 17 incl. Pro to Zorin 18 incl. Pro

I got Zorin 16, Paid for Pro as I felt it was worth it to support the Zorin project. Then Zorin 17 came along . I could find no way of upgrading 16 Pro to 17 Pro so I paid full price again for Zorin 17 Pro. Can I update from Zorin 17 Pro to Zorin 18 Pro without needing to pay the full price? I'm happy to support Zorin, and went out of my way to do so but a third iteration of having to pay full price does niggle. I am happy to pay a smaller fee for the Zorin 18 Pro but don't really think it's c…