This comment is not going to really solve your issue, but may help a bit.
You could change the values for the time the pop ups are shown on screen (settings -> pop ups -> change it to, say 4 seconds). Note that "zero" is NOT "zero seconds".
Also, you should note that the colour of the tray notification is not the same as a normal update.
As Asyn, I don't know why it is being displayed "so" frequently nor how to change that behaviour (other than renewing the license, of course).
In any case, the protection will stop if you finally decide not to renew the Pro license (AFAIK, you can't "transform" your Pro edition to the Free edition without uninstalling Avast Pro and installing Avast Free, but I may be wrong).
If you decide to renew the license, do it using the main GUI of Avast, so to "merge" the days still left of your current license with the new license (or consult with sales - a/T - avast D 0 T c0m).