Kimura didn't give the samples to Alchemax. She helped the Sisters escape and destroy Alchemax BECAUSE they got them (and she considers Laura her personal property).
We know she's not 21 yet from Civil War II (Logan asks if she's got something stronger than fruit juice and Laura asks Logan if he knows how old she is, so she's clearly not able to legally purchase alcohol). Keep in mind we do have a 16 month time skip in play here, too, (8 months between the end of ANXM vol.1 and Secret Wars, and another 8 months after that) so I'd be leaning towards the older end, at 19-20. Taylor was asked about it in one of his X-Pos but he didn't seem inclined to nail it down (and instead pointed to the upcoming CWII issue). Regardless, she's old enough to be keeping an apartment of her own and not have Social Services knocking down her door.
Unfortunately, that causes problems for her peers with the NXM, who are editorially mandated to remain students. If Laura is 18-20, most of them should be, too (even allowing for some age variance). So unless the school includes college-level courses they're not only being held back academically, but BIOLOGICALLY, as well.