There are at least two things you should look out for.
First of all, will the performance of your invention,
making, using or selling it, involve use, copying or
distribution of the software? If so, you need to check
your licensing status -- will your proposed commercial
activities be outside the scope of any license that you
Second, your patent application (specification) must give
an enabling disclosure of your invention. If you used the
software for demonstrating or developing the invention
in a way that must be disclosed in the specification,
does/did that use violate any license terms under which
the software was used?
'Proof of concept' is generally almost irrelevant to
a patent application and an invention. Your patent needs
to describe, not merely a concept, but an actual
invention, i.e. something new, unobvious and useful that
can be made and used with effect by following the
description in the specification. See 35 USC 112 and
corresponding statutes in other jurisdictions. Generally
speaking, concept and/or proof of concept might not
necessarily amount to a performable invention, and
in such a case the concept would not be enough.