Would be extremely useful when additional team members are only needed at certain times in projects.
Rather than having to add & remove team member seats month-by-month
Here's snippet from Slack regarding this pricing method
"Most enterprise software pricing is designed to charge you per user regardless of how many people on your team are actively using the software. If you buy 1,000 seats but only use 100, you still get charged for 1,000. We don’t think that’s fair. And it’s also hard to predict how many seats you’ll need in advance.
At Slack, you only get billed for what you use. So you don’t pay for the users that aren’t using Slack. And if someone you’ve already paid for becomes inactive, we’ll even add a prorated credit to your account for the unused time. Fair’s fair."