The only time a message is stored on WhatsApp’s servers is if the recipient cannot receive it (maybe they’re offline or don’t have a WhatsApp account). In cases like those, the message(s) you sent are automatically deleted off of WhatsApp’s server in 30 days’ time.
So this probably has you wondering if WhatsApp doesn’t store your messages on its servers, then where are they stored? The answer is, your WhatsApp messages are stored locally on your phone in the form of encrypted backups.
techuntold.com/where-whatsapp-mess...
Ah I didn't knew that, thanks for correcting me. Really interesting.