There isn't an in-place upgrade: each licence is separate, with its own key and its own number of sites. To cover more sites, buy the bigger plan on the Pricing page.
What happens to your 1-site licence
It keeps working. A one-time licence doesn't expire, so after buying the 10-site plan you have two keys in Account → Licences: one with 1 site and one with 10, for 11 live sites in total. Use whichever key you like on each site.
Moving your existing site to the new key (optional)
If you'd rather keep the 1-site key free for something else:
- In the site's Console, open Settings → Advanced → Licence.
- Under Replace with another licence key, paste the new key and press Activate.
- In webfaze.com Account → Licences, on the old licence, press Remove next to that site to free its seat.
What about a refund for the smaller licence?
The refund policy covers a first purchase that doesn't work as described, so moving to a bigger plan isn't a reason for a refund or a credit. The smaller licence stays yours and keeps working.
Extensions you bought carry over: a paid extension covers every site your account's licences run, whichever key they use.