Is the machine (exima) helpful to tighten the lose skin and remove stretch marks ?

No: Stretch marks are tears in the skin cause by weight gain. They can be covered up, but not improved by creams and lotions. The only possibly effective therapy is cosmetic plastic surgery, but that's a big step for a non-health and non-life threatening problem.

Probably not.: I haven't heard of the exima, but most external treatments don't do much for skin tightening. There is no good treatment for stretch marks except for surgical removal (like a tummy tuck).