If you select the one-time payment option, YES! You will have to pay just one time, and you will get access to the course and all materials forever.
If you select the 3 monthly payments plan, you will be billed the first payment at the moment of the purchase. The second 30 days after, and the third and final one after 60 days of the initial purchase.
In both cases, you will receive full access to the course immediately.