Regardless of the pricing option you choose, our system allows having only one active task per store at a time. When you submit a task, only after it is done and you mark it as completed, you will then be able to submit the next task.
Our system is set up in this way, in order to avoid having two or more developers working on the same store at the same time, as it could cause errors or even data loss.
However, if you are subscribed to the PRO or ELITE plan, you can draft up to 10 tasks, and then submit them easily one by one. Check the article below for more details about drafted tasks.