We have a standard pro annual account, but with 2 registrations under the same user. Let's say that a one year registration is $200, we paid $400 for 2 annual registrations under the same Standard Pro annual program, thinking that we could organize at least 2 simultaneous meetings.
With 2 licenses on your account, you will need to create 2 users to assign those licenses to. Likely the owner of the account already has one license, so you just need to create a 2nd user and assign the remaining license to them. Once that is done, each user can schedule and host meetings independently and simultaneously of each other.
Hope that helps and please make sure to mark the solution as accepted if this information is what you needed.