11 is too old for upgrades, you will need to buy a new license. If you are getting a group license, consider AVLA, which renews annually, has a lesser up-front cost, and always keeps you on the current version.
As for FMP 11 on Sierra, I would not recommend it. It *could* work, but you won't really get any support if something goes wrong.
Here's the official answer from FMI:
BTW, I have a mid-2012 macbook that runs sierra just fine. It does have max RAM and an SSD hard drive though.
That's also very useful info, am grateful. The new laptop will be supplied
through MR in London (who supplied the MacBook Pro I'm currently using) and
they have said its specs can be upgraded - bonus.
Annual Volume License Agreement.
Mmm prob too much for us, at present we have no more than half a dozen
computers, two of which cannot run higher than OSX10.4, and three others,
one about to be retired. However, we do need to investigate all these
options, and am grateful that you pointed that one out.