Windscribe, the free VPN, at least 10GB
Look at this wonderful software!
And affiliates can earn gigabytes or money itself...
Very user-friendly GUI of Windscribe can be seen below.
The software installs its own virtual network adapter, so the VPN Internet connection can be turned on almost at hardware level.
All you need to use this service with 10 GB is an online registration. Then you can invite users to earn gigabytes or even lots of money...