Two SigmaOne subscription, every course, and a tutor that knows exactly what you are working on.
A solution is one submitted answer — one per part on a multi-part question. A chat message is one message you send Sigmund; everything Sigmund says on its own is free, and skipping a question costs nothing. Both allowances refill on the same day every month.
Every month, on the day your plan started — monthly and yearly plans alike. Unused allowance does not roll over.
Your work stays exactly where it is. Move to a bigger plan to keep going now, or wait for the reset.
Anytime, from Settings. You keep access until the end of the period you have paid for, then move to Free. Payments already made are not refunded.
Only the price. The allowance is the same, and it still resets every month — you just pay for twelve months at once and save.