kramyugtaht :
Since this is about avast mobile, you posted in the wrong forum.
Hence why I was thinking ams4 could stand for Advance Mass Sender version 4

Upgrading to premium doesn’t happen automatically (or at least it shouldn’t)
Someone must tell it to do so.

Check the license status in the tool itself and on https://my.avast.com
What does the info tells you ? (licensed, trial or…)