How to increase GMail storage
Even though Google is currently providing almost 8GB of storage (and counting) for its GMail user, some might not find it enough for their use. Fret not, as Google provides additional storage for those willing to pay for it
Log in to your Gmail account and follow these steps.
Go to the Settings menu
Add additional storage
At the Settings menu, you'll automatically on the General page. Scroll down to the Add additional storage option
Click on the Upgrade your storage link to upgrade
There are few plans available. Choose based on your requirement and budget.
You'll then need to pay for the upgrade using Google Checkout