The Auction Dashboard highlights key License information (the plan and expiry date).
To view more detailed information, you can click on the License Button or access it through Organization -> License.
On the license details page you can renew your license or if you have an order number, click on Apply License.
You can also upgrade to a larger plan by just paying the difference in the price, but note that upgrades do not change the expiry date of your license.
On expiry, accounts revert to the Lite edition if not renewed but the auction data will remain accessible.