I paid Pro version, it says to be valid until 4.11.2017. After new update it does not work. I buy again, but I paid twice… 
Why so? Google account is the same. Now Pro version is valid to 2018.
The order is one year…
More information is needed if you want help.
What exact version of AMS ?
What exactly isn’t working ?
etc.
Version is the newest 5.12.1-14593-76a4335 which was istalled via google play today. After install my already paid licence do not work. I remove and install again, but not solve issue. I buy new licence and works but the previous experied 4.11.2017. New is valid 25.1.2018. So I paid twice for one year.
For billing issues, you need to contact avast as they are the only one who are handling them.
See > https://www.avast.com/faq.php?article=AVKB24