Hey Peter,
The API is only available in the IT Asset Data platform, so you’ll only be able to use data that you have synced to your site. The ADP does not have a specific version (since it is cloud-based, everyone is always on the same version). However, you do need the latest version of Lansweeper to be able to sync (once you have been approved)
In regards to licensing, there isn’t a specific license type that I can say yes or no to. At this moment we are evaluating whether access is allowed on a case by case basis, so it is best you contact your LS account executive or sales rep.
The documentation can be found here: https://www.lansweeper.com/kb-category/api/index.html
It is also linked in platform.