There are no restrictions on more than one person using Supermetrics with one license. 

But we do highly recommend creating different accounts for every user because it is more controllable for you (personnel changes etc.) and mainly because it prevents errors caused by simultaneous users with one account -which are quite common. 


Each Supermetrics license can be only connected to one google account at the time but please note that there are discounts for multiple licences on our webstore.

Related article: 

Can I add more than one Google Account for one license in Supermetrics for Google Drive?