In March 2019 the European Commission announced that the EWP standards will be mandatory from the beginning of the new Erasmus Programme. 

HEI should be connected to EWP from June 2021 onward when they should be able to support digital Inter-Institutional Agreements and Online learning agreements. The European Commission will consider the 2021/2022 academic year as a transitional year. This means that at the very latest before the start of the academic year 2022/2023, all higher education institutions participating in the Erasmus+ programme must be connected to the EWP Network and use it exclusively for their Inter-Institutional Agreements and Online Learning Agreements. Alternatively, they may lose their accreditation for the Erasmus Charter for Higher Education.

In practice there are 3 ways to do this:
A HEI implements the APIs itself
A HEI uses a third party software tool
A HEI uses the EWP/Erasmus Dashboard

A combination is possible, but you cannot combine tools for the same API service  (e.g. using the Dashboard AND commercial software simultaneouslty for Learning agreements)  

In practice, this means that HEIs can gradually introduce the changes, even though the EWP Network already has operational APIs for all of the processes in student exchanges as we speak. For a detailed description of the EWP APIs click hereOur third-party provider EWP partners (Mobility Online (AT), MoveON (UK), USOS (PL), Cineca (IT), Sigma (ES), FS (No)), have committed to implement all APIs in their business development plan, but the exact timetable is, of course, their own responsibility.  
Finally, the EWP/Erasmus Dashboard will be fully EWP compatible as of early 2021.

You could also start with one solution for a particular API service and later on change to another one, as long as you don't use two solutions for the same service at the same time.