Diego,
Go to the Support Operations folder and Deauthorize. It will list all the authorized single use license to deauthorize. You may have authorized a Basic or Standard license. If that is case, go back to the Desktop folder and change to the appropriate license level as Lauren mentioned.
It's possible you may have authorized ArcGIS Pro single use licenses. ArcMap and ArcGIS Pro use the same authorization wizard under the hood. You can use either applications to authorize/deauthorize ArcMap or ArcGIS Pro single use licenses. However, each application has its own license. You cannot use Pro licenses for ArcMap and vice versa. Check to see which license you authorized.