I am an Australian client - do I need to add GST to the cost of the licences?

It is our understanding that no GST is payable on licences of AB Tutor purchased online by Australian schools as AB Tutor is a 'non-resident supplier of a digital product' – See Chapter 4 of the Electronic Commerce Industry Partnership - Issues Register, Application of GST to supplies of digital products made to Australian recipients from non-resident suppliers.

As a non-resident supplier, AB Tutor does not have an ABN.