Nope! A participants in an event gets a free Crowdcast account that let's them browse and access Crowdcast events. You can also log back into Crowdcast to access all the events you have ever joined.
Participants only receive emails related to the events they've joined. Rest assured, Crowdcast doesn't send any marketing emails to them.
If you are looking to host your own live events over Crowdcast you can hop on the free trial here.
You can view the pricing for hosting crowdcast events here: https://www.crowdcast.io/pricing