After the design and development phase you can put the design into practice. During the implementation phase you gather data regarding the quality of the course/meeting, evaluate the students' reactions (was it a success?) and evaluate the students' learning.
A distinction is made between monitoring during the implementation and evaluating after the implementation. The monitoring phase is formative, this means that it gives you the opportunity to make improvements during the implementation. Evaluation is summative, this means you can draw hard conclusions regarding the quality of the course.