I bought parallels 7 or 8 and then had to pay to upgrade it to 9/10 so I could run it on mavericks. The latest email now says I need to upgrade again if I want to upgrade to el capitan. The link shows I must pay for the upgrade again. Surely we don't need to buy a new software licence every time apple force an update on us.
Depending when you bought PD 10 you may have to pay for PD 11 upgrade. I'm in a similar situation I bought PD 10 < year ago and now I have to pay again for PD11. My advice to you, if you are happy with PD 10 don't upgrade. Parallels changed the max RAM/CPUs for the standard version so, if you need more then 8GB RAM in your VM you'll need to upgrade to Pro version which is a subscription model Personally PD10 is my last investment in Parallels unless they change few things.
I'll probably just leave it along then, and worry about upgrading when something doesn't work. Looks like a fairr bit of scare mongering to get people on to the new parallel subscription. I oddest like these subscription agreements in general. Many are going down that route, even microsoft. It's different with things like antivirus when you need continual updates, but most apps should be good as long as there are no bugs to be fixed.
