How long does the effect of the blemish treatment last? I'm worried they'll come back soon.

My melasma and freckles have gotten noticeably darker, so I'm thinking of getting a laser treatment to completely remove them. However, my biggest concern is the 'duration of the results.' I've heard that even if you spend a lot of money to get them clean, the spots start creeping back in after a few months. Is it worth the money?

To be honest, I can't quite tell if my skin goes back to how it was quickly if I neglect aftercare, or if getting rid of the blemishes properly once will keep it looking good for a few years. I really hope it's the latter... Even if I apply sunscreen diligently, there must be a limit to how much I can handle daily life. How long did your clear skin last after your blemish treatment?

I'm worried I might be spending a lot of money for no reason, just for temporary satisfaction.