Good question, Peter. The answer is “it depends” 
API key usage will be consistent with the data access policy that we posted about a year ago, but haven’t begun fully enforcing yet. To summarize:
Normal API keys (which will be available to any user - no special agreement required) will require personal access tokens (or Oauth2 authentication) to access only the authenticated station owner’s data.
Enterprise API keys (which will be issued upon request and may require a special agreement with WeatherFlow) may still allow access to data from multiple stations, without a personal access token. These are taken on a case-by-case basis.
Please hold off development of that for now. We may want to convert your API key to “enterprise” with some special access that satisfy your use case. We will also be adding a “share” feature soon that allows station owners to share their stations with other users, which may also satisfy your use case, but the details are still being worked out.