Can we use other cloud services after I have programmed my photon with spark cloud services for commercial purposes.
the firmware of Spark devices are all open-source so you are free to do anything you want with it. 
See: https://github.com/spark/firmware
There’s is no cloud lock-in and users are free to not connect to the 
!
The only issue is you will be missing out a lot of fun features 
If you are interested in making commercial products, Spark HQ has a ton of new tools coming up to help people like you!