Use the following method for logging new membership creation transactions.
The OM.exVisitorID parameter should not be empty. One of the user's email or userid information should be assigned to this parameter.
If you do not know which of the email or userid values to send to the OM.exVisitorID parameter, contact the RMC team.
let userData = {
"OM.exVisitorID":this.user.keyID,
"OM.b_sgnp":"1"
};
visilabsApi.customEvent("SignUp",userData);
You can review the sample usage in line 58. on this page.