Please follow the steps bellow if the update message is not displayed.
[Updating manually]
1) Press the 'Update' button on the bottom right corner of your Appstore
2) Press the 'update' button next to the PUBG Mobile app icon
[Updating manually]
1) Press the 'Update' button on the bottom right corner of your Appstore
2) Press the 'update' button next to the PUBG Mobile app icon