The different pricing plans are determined by how many users you have, the number of projects you can have is unlimited.
If you try to exceed your plan limit of users you will be advised that you will first need to upgrade to the next plan before you can do this - it will NOT happen automatically.
Annual vs Monthly
We also offer annual plans whereby if you pay for a year's subscription upfront you will receive two months free.
Note: unused time on annual plans if you cancel is non-refundable.