Is it permissible to work as a medical aesthetics device sales representative, knowing the impermissibility of the field of aesthetics, and given the tempting salary, and is it possible to leave the job and repent after having earned from it?

It is permissible to advertise and market medical devices used in cosmetic procedures, provided they are not used in forbidden acts such as plucking eyebrows (namṣ) and tattooing (washm), because it is not permissible to sell anything that aids in disobedience (to Allah). It is permissible to market to those who use them for permissible purposes. If the buyer's intention is unknown, and the devices can be used for both permissible and forbidden purposes, then marketing is permissible. The basis for this is Allah's saying: ﴿وَتَعَاوَنُوا عَلَى الْبِرِّ وَالتَّقْوَى وَلَا تَعَاوَنُوا عَلَى الْإِثْمِ وَالْعُدْوَانِ وَاتَّقُوا اللَّهَ إِنَّ اللَّهَ شَدِيدُ الْعِقَابِ﴾ (Al-Ma'idah/2). Everything intended for unlawful purposes is forbidden. So, if the seller knows that the buyer intends to use it for an unlawful purpose, the sale is forbidden. However, if the seller does not know or is in doubt, the majority of scholars permit it.