Do not get lured in a trap of giving out your personal information like passwords/making payment etc. as Gmail subscribers are receiving a fake email which is supposed to be originated from Gmail (though it is a spoof email) and is asking you to upgrade to higher plan of Gmail by making additional payment. The below screenshot is of an email which we received in email inbox. Gmail is a free service and never asks you to share your info and never ask for money. The fake email originator email id is attached in adjacent screenshot. However they are shrewd and can change the email id at a drop of hat to trap you.
If you want to upgrade to any of their service than do so from their official webpage and not from a link in email.
You can check out other fake Gmail here.