License Upgrade

My Premium license expired last week and I did purchase a new premium license, but cannot seem to enter the new license key or find the area to do it.
Where/How does one do that?
It seems that you have to uninstall Avast from your Mobile devises and then re-install it again to be able to enter the new license code?
Can anyone help me here?

See: https://forum.avast.com/index.php?topic=170042.0