The magento plugin can be modified but the code generated for Andriod and iOS cannot be modified with the existing plugin cost which is for USD 399. Right now the mobile binary is generated from the server at our location when the magento website hits the server.
If you need the source code for the mobile app, I can provide it for an additional cost of USD 400. You will be able to use this code and modify it for your customer's website. If you need additional license for multiple domains, let us know.