absolutely!
Every kind of derivative works belongs to You and you alone!
Any kind of derivative works can be sold in any fashion and under any licence YOU want.
However, you may not bundle or re-bundle any part of LMMS in any sale!
Let the community know, if you have an success selling your derivative works :)
Besides that, since you are new in Forum
Welcome Nazarete !
Here are all important links:
http://lmms.io/forum/viewtopic.php?f=1&t=4740
-A few rules and useful forum instructions