I tested upgrading when MC 11.0 was new and wrote some instructions:
http://yabb.jriver.com/interact/index.php?topic=27914.msg194327#msg194327You may want to read the complete thread. Based on my experience of MC11.1 I think the instructions are still valid.
Shortly, it goes like this:
- Backup at least your MJ8 library (it has a backup tool).
- Uninstall MJ8.
- Install MC11.1.
- You can buy MC11.1 from inside the program (If I recall correctly the Help menu has a buy link). The first splash screen has an additional "buy" button if your trial period has already expired. Because you have had registered MJ8 installed the purchase system should offer you the upgrade price. Don't proceed if that does not happen for some reason; ask help here instead.
- Restore your media library backup file in MC11.1.
... but, please check the link out. It has more important information.
EDIT
I am not sure if you are going to upgrade to MC11.0 or MC11.1. However, both versions work with the same license.
One thing that I have not tested is restoring an MJ8 library backup directly in MC11.1. At least that works with MC11.0.
If you are going to install MC11.1 and restore your MJ8 library backup, please tell us how it went.