I downloaded all the OpenNETCF dlls. Is it free? Or will it stop working after a year?
If you mean the Smart Device Framework (migrated from Codeplex), then yes the binaries are free to use and distribute. There is no limitation in features or time on them for any edition, including the free Community Edition.
If you mean any of our other products or libraries (we've got quite a few), then you'll have to be a bit more specific.