I purchased the wpdiscuz-mycred plugin, but the activation key won't work.

The plugin was purchased on June 20, 2025. When attempting activation today, the key failed to work and produced the error shown in the attached image. My current versions are: wpDiscuz: v7.6.3 wpDiscuz myCred: v7.0.6 I haven't updated to newer versions because I've made custom modifications to the plugin.