Controlling seats in apps used in a company - what do you think?

We have that problem in the company I work for (software house).

We use a lot of saas applications, like Github, InVision, Jira, etc., and different employees have a different kind of access to them. Sometimes we give access to some of these apps to our clients.

It's very difficult to control who has what kind of access to which apps.

We waste money on seats that we no longer need and we are concerned about safety (e.g. because someone doesn't work with us anymore but still has access to some of our apps).

I came up with the solution: https://holdseats.com/

What do you think about this? Have you noticed a similar problem? Would you use something like this?