My avast is about to expire, i don’t wanna get charge for a renewal, what do i need to do?
Disable the auto-renewal.
How is explained many times already on this webboard already.
Please use the search option before posting.
Welcome to the forum. 
This should help:
Disabling Automatic Renewal service for Avast orders distributed by Nexway
https://www.avast.com/en-us/faq.php?article=AVKB136#artTitle
Disabling Automatic Renewal service for Avast orders distributed by Digital River
https://www.avast.com/en-us/faq.php?article=AVKB126#artTitle