If you use LabKey APIs that extend the Ext API, your code either needs to be open source, or you need to purchase commercial licenses for Ext.

For further details, please see the Ext JavaScript licensing page. An excerpt:

"Based on the "Quid Pro Quo" principle, if you wish to derive a commercial advantage by not releasing your application under an open source license, you must purchase an appropriate number of commercial licenses from Ext. By purchasing commercial licenses, you are no longer obligated to publish your source code."