The official free version of PhotoPad is (trial), after which it becomes a reduced-feature viewer/editor unless you purchase a license. There is no legitimate permanent free registration code — any code claiming to unlock the full version for free outside of NCH’s official channels is pirated.
While the desire for a free registration code is understandable, especially for those on a tight budget or who use the software sporadically, it's crucial to approach this from a legal and ethical standpoint. Here are some considerations and potential avenues: photopad registration code free
Sites that require you to enter personal info or "verify" your identity before giving a code. The official free version of PhotoPad is (trial),