For new purchase and renew you have two options
1. Purchase Online (Pay by Credit Card for Month or Year)
2. Purchase Volume License (Purchase from Vendor / Partners)
*** first time redeem code please click this link https://portal.office.com/Commerce/ProductKeyStart.aspx?ms.officeurl=setup365
Volume License renew can change to use credit card, temporary i still don't know how to change credit card renew to volume license key, i should waiting the term end date to try the options..
How long about Volume license purchase process
Purchase the volume license, Vendor/Partners just take within few working hours to place the order from Microsoft, user will get the following e-mail for activate the product, actually almost next working day you will got the license from e-mail.
Start the Activation Process
Step 1. - After order the license, you will receive above mail, you can click "Please click here to get started with your online service."
Step 2. - Check your Organization Name if correct, click the below "Sign-in with your domain name"
Step 5. - Choose "Use a new and unused product key"
Step 6. - Enter the product key
Step 7. - You can renew current subscription or add 1 user license, the following will explain more about the difference.
Add new user license on existing subscription can apply on the following situration :
- This is a way to change online payment back to volume license
- Add new user license and make all license as same term end date, you can check the picture description how to calculate the service month if you add the new license.
Renew your subscription just is renew only.