We don’t have our FDS course on Guvi, it’s available only on PadhAI.
On PadhAI, since the hosting and maintenance is taken care by us, we have a limited duration access to the course materials.
The validity is mentioned so that people are encouraged to complete the course soon without procrastinating; it is not hard-set or non-modifiable.
For instance, “many” (around 60-70%) people who enrolled in our February 2019 DL course have not still completed the course yet, and we have been requesting them to complete as soon as possible by means like this. It’s more of a way to indirectly encourage people to complete the course.
There has been a lot of studies on dropout rates of MOOCs, please check it out.