How can I be sure I am using the latest version of the app?

For more transparency and a better overview: new version numbering of the Nuki App releases. 
At least once a month a new app release of the Nuki app is published. The best thing to do is to set your smartphone to update apps automatically. This way you can make sure that you always use the latest version and benefit from all features of your Nuki device. 

For iOS, you can activate the “App Updates” option under “Settings” > “App Store”. 
For Android, go to the top right of the profile icon in the Google Play Store app. Now select “Settings” > “Network preferences” > “Auto-update apps” in the settings. 

In the menu, under “Help” at the bottom, you will find the app version you are currently using. 

How is the version number composed? 
The current format is composed of year, month and release number. So the last number shows you if it is the first release of the month. That means the first new app version in March has the following version number:
Year.Month.Release 
2022.3.1 

Why was the current format introduced? 
In the past it was not always easy to keep track of current app versions. Until now, the current app version has been identified by a sequential number (e.g. 3.1.0 (654)). And that's exactly what we wanted to change: The naming should become clearer, easier and more informative for you. With the new format you can see at a glance when the version was released. Because the new format will also include the release date. 

Will the current format also be introduced for firmware versions? 
No. The current format is currently limited to the Nuki app. Version numbers of firmware or web are identified by a sequential number.