Study.com Subscription Question

[lacussucceed]

Yes you can complete the quizzes and assignments BUT you have to have the College Accelerator plan to turn them in and get graded for credit.  What I do with mine is this:
One month on Premium plan studying 1 course (you could perhaps study 2), then sign up for Coll Acc plan, take that exam and study for and take the 2nd exam before the month is out.  This gives mine time to prepare but they are only 13 yo so an adult may well be able to study for 2, take the 2 exams and still study for and take a 3rd exam.
The cost ends up being $130/3 credit class but, obviously, if you can do more in that time the cost will be even less.

You don't need College Accelerator plan to turn them in, ask for a link to submit without a membership and they will provide it.
You can use college accelerator to power trough quizzes, check the requirements of the assignments and take the exams, next pause and finish the assignments.