Is it ok to leave Macbook Pro plugged in all the time?

Personally I think it's okay to keep your Macbook plugged in since it uses the Power Adapter as its power source when plugged in, it will not exhaust the battery

Should Unplug at least once a Month and use on battery for some time . This will allow the chemicals in the battery to get exercise of discharging and recharging.

You can keep your MacBook Pro plugged in for a while without any problems. It's not a good idea to do it all the time, though. Mac batteries are designed to recharge and discharge over time.