Praise be to Allah.
The basic principle with regard to aphrodisiacs is that they are permissible, so long as they do not contain anything haraam such as intoxicants or drugs, or cause physical harm.
What is usually the case is that licensed remedies that are permitted to be sold do not contain anything that causes harm, even if they may cause harm to some people.
In this case, there is nothing wrong with selling them, but the purchaser should look for something that is suitable for him, and he should consult a doctor about that.
With regard to those that are not licensed, they may indeed cause harm, so it is not permissible to use them or sell them.
Licensing bodies have the authority to regulate the sale of medicines, and to protect people from that which may be harmful to their health.
One of the addictive tranquillizers that it is not permissible to sell except with a medical prescription is tramadol.
Moreover, it is prohibited to sell these aphrodisiacs to one who it is thought most likely will use them for immoral purposes.
It says in Kashshaaf al-Qinaa‘ (3/182): It is not valid to sell anything that may be eaten, drunk or sniffed to someone who will consume intoxicants with it; or to sell vessels that usually used for drinking alcohol; or to sell eggs, almonds and so on for gambling; or to sell male or female slaves to one who is known to engage in homosexuality or for singing, or to hire them out for such purposes, because all of that comes under the heading of sin and transgression.
For the ruling on taking tramadol, please see the answer to question no. 153893.
To sum up:
Your husband must limit it to only selling licensed aphrodisiacs that it is permissible to take without a doctor’s prescription.
It is permissible for a marketer to be paid a salary or commission, or a percentage for every product he sells.
This is a fee, and it is permissible for the fee to be in the form of a set amount or a percentage of the price or of the profit, according to whatever is agreed upon.
It says in Kashshaaf al-Qinaa‘ (3/615): Hiring someone to sell a product on one’s behalf in return for a percentage of the profit is valid, and collecting money for him in return for a percentage of that is also valid.
And Allah knows best.