Powering Arduino pro trinket with cable and power source

I have an Arduino pro trinket 5 volt board. I have the board hooked to my laptop using a FTDI Cable.
I have done a few simple experiments using the IDE such as blink and I have even lit up an external LED using the board.
I am building a simple circuit that takes a 9 volt battery and runs it through a voltage regulator to produce 5 volts. I want the arduino to run off the battery. Can I run the arduino off the battery and use the FTDI hooked to the computer or is this risky?