How many sessions should I consider when calculating the cost of a melasma skin booster?

I am writing to inquire because I am wondering how many sessions I should consider when calculating the cost of a melasma skin booster.

I have an important photoshoot scheduled in about two months, so I would like my skin tone to look at least a little more even before then. My face isn't generally dark, but the freckles on my cheekbones make my skin look dull, and even when I apply makeup, that area looks heavy and lifeless.

I know that a melasma skin booster isn't a procedure that immediately removes pigmentation, but I'm wondering if it can help improve my skin condition so that makeup doesn't cake as much and my skin looks less dull overall.

Is the cost for melasma skin boosters usually calculated per session, or is it often based on a recommended number of sessions, such as 3 or 5? I would also like to know how many weeks in advance I should start the treatments to get them ready. If I mention my photo shoot date during the consultation, will you adjust the cost and treatment schedule accordingly?