Instructions to forestall various clients to join online course with same connection

Hello all,

I have an issue in online course.

I'm utilizing the wordpress module for the gotowebinar.
I have paid online courses.

the issue is, the point at which somebody buy the online course from my WordPress site then, at that point, he got the online course joining join.

assuming I share that connection with numerous clients then they additionally join the online course without paid.

I need to forestall this.

anyone can help me?

If it's not too much trouble, reply as quickly as time permits.