Office 365 Education states its a trial but advertised as free

I have created a "free" Office 365 for Education domain for a customer, but once created its stating its a trial under billing. 

I signed up here:

https://products.office.com/en-gb/academic/compare-office-365-education-plans

I don't understand how I've signed up and its suddenly a trial? Am I missing a process somewhere?

Thanks