With the Arc Analytics annual plan, you can adjust the number of projects your team uses at any time.
When you add a new project, you can use it immediately and your account will be charged a pro-rated value based on how much time is left in your billing cycle.
When you remove a project, you will retain access to that project space for the rest of your billing cycle. You've already paid for access, so can re-add a project with no change to you billing at any time.
If you don't want to re-add any projects, your account will be charged less at your next billing cycle.
Annual plans and unused projects are Premium Arc Analytics features.