On the Activation Code page:

Single Activation: Enter the code → Click Query → Select a new device (default or choose target Android version) or renew an existing device → Click Activate Now.

Bulk Activation: Enter the codes → Select default or specific Android version → Activate to new devices.

Bulk Renewal: Select the devices you want to renew → Enter the codes → Click Renew (the number of codes must match the number of devices).