Check the application and the download page
Look at the version information in the installed application, and compare it with the version shown on the official download page. Use the product’s current download destination when installing an update.
The release notes provide the context for changes between versions. Automatic updates arrived with NotchNook 1.6.5; the download page remains the direct route to the current application.
Use the current update instructions
Follow the installation guidance on the current download page when moving to a new release. It explains the Applications-folder step, the first-launch confirmation and the access prompts that can appear when moving from an earlier version.
After opening the updated app, compare its displayed version with the download page. Recheck the feature you use most and, if you use Launch at login, check that setting too. A successful download and a running current version are two separate checks.
Use the number in a useful report
A short report can begin with the NotchNook version, macOS version and the feature involved. Add the action you took and what appeared next. This is enough to avoid a long exchange just to establish the environment.
If the question is about a current purchase or activation, use the license-help page as well. Keeping a version question and the purchase reference in the same support conversation helps the team follow the complete situation.