In order to upgrade your uWebChat subscription, you can either type Upgrade or Upgrade Subscription in uWebChat.
After the command has been entered, a rich card will appear, prompting you to enter an existing key or to acquire a new key.
If you choose Enter Existing Key, a new rich card will appear in which you can activate your license key.
If you choose Acquire New Key, a link will appear which will redirect you to Microsoft AppSource. On this page, you can acquire a new licence key. Once the licence key has been acquired, you can type Upgrade in uWebChat and enter the newly acquired licence key.