Free sewing patterns are given to supply a need to newborns in need, charity work, etc. and returning the finished work to the organization supplying pattern.
You must ask permission to use the pattern for commercial purposes. If you do not ask, then changes must be made to the pattern, whereby the pattern is similar, not exact. In some instances, one can create a pattern and see it on another site.
If you create a pattern and see it somewhere else, without permission and your proof of a copyright or pattern, you can contact that person and ask not to use for commercial purposes. This is what the "free" means. Without permission, you cannot use.