PIC mcu memory question

Unless the top surface of the chip has been ablated, sanded, or etched, you can normally quite easily read the part number.

 

Google will be your friend.

There are a number of attack vectors, which one (if any) will be effective depend on the chip, how it is protected, possibly how many samples you have, and what your funding is like.

One method is to carefully monitor the current draw as the device operates and from that determine what it is doing.

Another method is to dissolve the chip's epoxy covering and use a scanning electron microscope to look carefully at the die. Apparantly with some types of electron microscope you can "see" charge.

Other ways involve doing stuff to the chip to corrupt the contents of that part of the chip holding the "protection" or making it spit out code or values.

This was once a far easier thing to do than it now is as chip manufacturers are learning from this stuff and improving their products.

Here is some very old information. And here too. Apparantly if you can afford $US9k you can get someone to do it for you.