Can I run lot of devices in free version ?

✅ YES. There is no limit to the number of devices you can run, but Genymotion Desktop is not designed for parallel use and running more than two at the same time will likely cause major slowdowns and instability. See How many devices can I run simultaneously? and the Genymotion Desktop pricing section for the free plan limits.

If you want, I can also tell you which free-version features are limited besides the device count.