Education

If you are having 1-on-1s and still being limited to 40-minutes, that means you've had too many people join the meeting. Zoom counts the number of joins to a meeting, not the number of different participants, so if someone connects, disconnects, and rejoins, that counts as 2. With you being the 3rd join to the meeting, that would trigger the 40-minute timer. 

If you have a situation where someone disconnects, its best to close the meeting on your end as well, in order to fully end the meeting and reset the timer, then open the meeting again. 

Beyond that, there is no way to extend a group meeting beyond 40-meetings for free.