I had a situation recently, where I had to install Microsoft Office 2013 on a computer that didn’t have internet access. Office 2013 is not sold with disc, but with a product key card. Here is how I managed to install Office 2013 completely offline. You will need Internet access one time to download the disc image of Office 2013, after you have the disc image you will be able to install Office completely offline on other computers.
Set up a Microsoft account for the customer. You can sign up here.
Next go to www.office.com/setup and sign in with your Microsoft Account.