If I switch jobs, and my new employer has an HSA, am I allowed to use that HSA to pay medical expenses incurred in the past (was using employer's HSA to pay)?

I have an HSA through my current employer, and have been using it to make monthly payments for a medical bill I incurred while having the HSA. If I transition to a new job with a new employer and a new HSA, can I use the new HSA to continue making payments towards my medical bill? Or is there a way to use my old HSA at the new employer?