It is possible to have a yogi attend a class or workshop without having an account with Momoyoga. However, with Momoyoga you can keep track of your administration and you will see the purchase history and classes being attended by which yogis. Without an account, no registration can take place via Momoyoga.
A possible solution is to create a yogi account (an open profile) with a fictive name and a self chosen email address which is not yet linked to Momoyoga, this may also be a fictitious address. After all, no purchases can be made by the yogi without their own account. You can use this open profile to book classes, this way you can manage the available spots of your classes. These spots will all have the same fictive name.
As soon as a yogi is attending classes or workshops more often, a personal account would be better. If necessary you can set it up without a valid email address. The yogi won't be able to login but you can register the yogi attending classes and if a payment has been made.