Huge problems installing Parallels

Scenario:
1. My Mac running OS X 10.9.5 / Parallels 10 / some P10 VMs since 2017 - NO PROBLEMS
2. Fresh installation of 10.9 on external SSD which I will clone back when ready. The problems are with this:

• despite copying all Parallels files from Mac > SSD , Parallels launches as if a new installation, and shows an old email which is NOT my current email with you.
• I therefore copied across a download of archived Parallels 11 which is the last version which will run in 10.9
• Parallels 11 installed successfully on the SSD and in the first window I input my current email and password (accepted)
• However, as it's an archive download, there isn't an activation key. "No worries" I thought "I'll 'Try for14 days' and sort things out during that time"
• Unfortunately, when I clicked Try, it just said I must be connected to the Internet - I was!!!!
• So I clicked Buy instead, as upgrading to P11 would not be a complete waste of time. Unfortunately clicking Buy took me to your website page for P16 which won't run on my machine. There seems no way to pay for an older upgrade and get an activation key.

Parallels, is your official policy that no-one should run older versions, or buy them? Please, help me or you will lose a customer.