Encog is switching to the Apache License 2.0, as of Encog 2.5. This should have minimal impact on most people using Encog. The Apache License is a free open source license. It is very similar to the LGPL, which previous versions of Encog are licensed under. You are still allowed to use Encog in commercial and non-commercial projects. You are still encouraged to modify the source code, and not required to release your own source code.
The main advantage to the Apache License is it allows better compatibility with other projects using the Apache License.
The Apache License 2.0 can be found here here.