Printing PLA on PEX surface - is heated bed needed?
I print PLA on a PEI bed at 60°C.  I have also printed PLA on an aluminum bed at 60°C with Elmer's Glue Stick for bonding, which worked better for me than PLA.  I recently switched to Aqua Net Hairspray on the aluminum bed at 60°C, which also worked well.

I have found no reason to avoid bed heating with PLA.

If the object is stuck too tightly on the PEI bed, you could try adding hairspray.  It acts as a glue, but also as a release agent, and, being soluble in water, you can help release the object with a few water drops.