Do I tip for a hydrafacial?

I've been getting hydrafacials for a few years now. I go to the same girl everytime at a med spa. I am so confused though. I dont know if I should be tipping because when I go to pay they never ask me if I want to leave a tip and they don't even hand me a receipt or anything like that. Like I don't even know HOW I would tip here unless I'm just handing over cash directly in the treatment room, but that seems a bit rude? like "here's some pocket money for you, thanks for cleaning my face"

I know that some places are gratuity free but i have no idea here!!

I've just always been getting the upgraded facial which is more expensive due to being unsure of their tipping structure