I rebooted my machine from a earlier moment and avast didn’t remember the licence key, i don’t have it anymore and can’t activate avast.
What do i do now?
Avast home or pro?
If Home:
Go to the website and get a new key.
If Pro:
Contact your reseller or Avast and request reending of the key.
This is it i guess?
It says invalid licence number when i cut an paste 
Make sure there is no trailing space when you copy/paste, also make sure your system time/date is correct.