Allow upgrades without login in

I have a system where users first sign up using a free membership plan (No CC required)
I then want to allow them to upgrade their membership to a paid plan.

I wanna have a URL anyone can get to, enter their email and CC information and process the upgrade.

The current Login->Upgrade->enter details is too cumbersome to get conversions.

I need membership pro to not register the emails on the upgrades but simply update the email related to that account

As far as I know that is not a feature of Membership Pro.

Any suggestion or work around?

Sorry Luis but we don't have solution for this requirement. To update membership, users need to have an account, login, then access to upgrade memnbership or user profile page to see list of upgrade options available and choose the upgrade option he wants to process upgrade

Regards,

Tuan