Is there a way I can use it as secure key to lock/unlock my laptop. I know its as a proximity sensor, can that be used to see if I am near the laptop and then unlock it when I am there and lock it if I move away.
Please help.
We have not tested one of these apps, but it seems that there are some solutions which can use bluetooth low energy proximity to unlock a laptop: https://www.howtogeek.com/222924/how-to-unlock-your-computer-with-your-phone-or-watch/ .
Security is somewhat tougher issue, as there is no spoof-proof ID in RuuviTag as of right now. It might be possible to write a program which scans nearby bluetooth devices and uses secure, encrypted communications to exchange the password to unlock your device.
Please let us know if the linked programs work for you, we’re always happy to see new creative uses for RuuviTag 
I have gone through the link. But this is not good for Linux or Windows systems.
There is no way currently that can work with any laptop with any operating system.
I am not a developer but have ideas which can help and make difference.