The Google support page gives information on how to make sure apps installed via the Google Play Store are up to date.
To check if you have the latest STV Player app version follow the steps in the section labelled "Update Android apps manually". If there is no notification of an available Update for the STV Player app under the UPDATES tab; or if there is no UPDATE label next to the STV Player app under the INSTALLED tab then the app will be up to date.
All customers should ideally make sure their Android apps are set to auto update.
https://support.google.com/googleplay/answer/113412?hl=en
Example photos of what can be seen via Google Play Store on my phone attached.