Go to the License Section and copy & paste your license in the given area.
Click on Activate license.
Click on Manual Update.
Click on Update Now. (In right bottom corner as shown in below image)
After the update, WPNakama plugin gets deactivated automatically because of version shift. So, now you just need to go to Plugins > Installed Plugins > Below WPNakama, Click on Activate.
DONE.