Each Worksoft SaaS subscription level comes with a:

• ‘Daily Capacity’ (maximum number) of hours of test execution allowed/day, and a 
• 'Maximum Concurrency' that allows you to execute tests in your parallel to reduce the overall time it takes to finish all your tests. 

Except for the ‘Daily Capacity’ and 'Concurrency' differences all subscription plans of Worksoft SaaS allow you to have an unlimited number of projects, users and offer you access to 100% of the rich and powerful feature/functions within Worksoft SaaS.

To decide the subscription level of Worksoft SaaS, you need max number of hours of automated tests (aka "Daily Capacity") you (and other users within your company that will use Worksoft SaaS) expect/need to execute per day across all your projects across all the combinations of browsers/operating systems and devices AND the level of parallelism you need (aka "Concurrency").