No, the same credentials can only be logged in on one computer or device at a time. If several people need to use Sarbacane at the same time, each one needs their own credentials and their own licenses.
Caution: if someone logs in with your credentials on another device, you are logged out and any content being edited may be lost.
To add a user and assign them a license: have the Owner or Administrator role.
Have a free license for each application the person needs.
Add the person as a user of your account by following How to add a user to your Sarbacane account?.
Assign them a license for each application they need by following How do I assign a license?.
If you have no free license left, buy one on the Sarbacane Store by following How do I purchase a license?.
Each person logs in with their own email address and password, on their own device, without logging the others out.
Someone has probably logged in with your credentials on another device. Give that person their own access (steps above), then change your password.
All your licenses are already assigned. Buy an additional license, or remove a license from a user who no longer needs it by following Can I revoke a license assigned to a user?.
