FreeLing is licensed under Affero GPL.
Some modules or linguistic data are obtained from external projects, and they have their own license and copyright owner.
Check the COPYING file and LICENSES folder in the distribution to find out which conditions apply to each module.
Affero GPL forbids distributing proprietary software that links to FreeLing, as well as using FreeLing as a component in a proprietary web-service. If you are interested in doing so, we can provide a dual license that suits your needs.
You can contact us to find out the conditions.