You "purchased" ArcGIS for Desktop for Student use, interesting...from whom?
Are you at an academic institution? If so, your ArcGIS Pro licensing would be delivered via your Institutions ArcGIS Online (AGOL) organizational accout. They would provide you with the installation packages for ArcGIS Pro. Your licensing would be by named user linked to the AGOL account.
ArcGIS Pro does have Single Use licensing (via conversion from Named User seats on MyEsri portal) and now Concurrent use licensing--but those are not the norm.
If at an Academic institution with a Esri Education program license, you'll need to figure out whom your campus contacts are. They'll be able to help you out with accessing ArcGIS Pro.