On the My Products tab, there is a listing for each of your purchased serial numbers.

On the My Products tab, select Manage Product for the relevant serial number and scroll down to the Activation Details list. If you have an active subscription, either contact the PEERNET team to deactivate a computer that no longer in use or use the Deactivate button if that option is available with your license.

On the My Products tab, select Renew Subscription for the relevant serial number when your expiry date is coming up.