I recently used a library from http://www.braemoor.co.uk/software/index.shtml (the EU VAT No validation library at http://www.braemoor.co.uk/software/vat.shtml) in a project at work. It mentions as the license (or something that looks like one):
All software is provided as freeware for personal or commercial use without obligation by either party. The author will not accept responsibility for any problems that may be incurred by use of this software, although any errors reported will be corrected as soon as possible. Re-distribution of this software is NOT permitted without explicit permission.
I checked the code and found (and applied) a few ways to improve the code so it's more easily maintainable and more readable (you can find one of them on CodeReview.SE). After applying these changes, I considered that others might benefit from them as well and sent them as feedback to the author on his contact address. A few hours later, the author sent a reply thanking me for my suggestions, and that he would go over my changes and keep me informed.
My main concern is that while the website mentioned that it was freeware, I'm not sure how far I am allowed to go in altering his software without knowing the license. I assume it's license-free, but it's not specifically mentioned as open source, and I'm slightly worried that I might have overstepped my bounds and took too much liberty with the whole thing.
Did I do the right thing?