I logged in to my account at my desktop, can I open my account on other device at the same time?

Yes, with your valid login details, you can open your device at multiple devices at the same time. It is generally the case when the user is login at desktop/laptop but can’t use that at a moment. At that time, he/she is authorized to open his/her account at mobile device or another desktop/laptop to have access to the purchased products/services.