I am borrowing a friend's DJI Mavic Pro and was wondering if i need to reactivate the drone to use it on my phone instead of his?

Hello and good day Jere_Ana. Thank you for reaching out and for the inquiry. You do not need to reactivate the said DJI Mavic Pro. All you need to do is to download the DJI Go 4 application on your mobile device and you are all set to go. Just a friendly reminder to use a recommended mobile device when using or flying the DJI Mavic Pro for compatibility and reliability purposes. I will post the list of recommended mobile devices for reference. Thank you.