SaaS Architecture Question

Hello all!

When reading an article about freemium SaaS models, the author brought up an experience where initial users were abusing the paid subscription when they upgraded by distributing one account among their entire team via one user account.

A little context - a B2B product I've been developing charges "per seat" for a pro version, but I never considered the previously mentioned scenario. Currently, I don't have any way to monitor user login activity (i.e. from a different IP address) therefore I wouldn't be able to tell if this is occurring.

What's your perspective on this scenario? Also, from an architecture standpoint, what system design would you recommend to prevent this from happening?

The idealist in me is saying not to fret over this too much, but I wanted to get some other opinions from this amazing community :) Thanks!