Start ArcGIS Pro. On the start page, click Settings in the lower left corner. In the list of settings on the left, click Licensing. On the Licensing page, click Configure your licensing options. On the Licensing dialog box, select ArcGIS Online or ArcGIS Enterprise according to the type of ArcGIS organization you belong to. Replace the URL of the current licensing portal with the URL of the new licensing portal and click OK. Restart ArcGIS Pro and sign in.