Firstly, FMI has decided to leave the FM11 trial version on their website for people who need to use it on the way from converting FM2-FMP6 files into FM12 format.
If you need a license code that will last longer than the 30-day trial period, try contacting FMI sales, they may be able to work something out for you.
-- Drew Tenenholz
FMInc will generally provide a Downgrade for a few dollars if you've bought the lastest version.
Contact FM Sales dierectly to discuss the details.