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One of the common transactions is the payment of key money. The right of key money is that the lessee reserves the right to clear and sublease the leased item itself to another party, or that the owner does not have the right to increase the rent or to take the rented item itself from the lessee.

2877. The validity of such a transaction is contingent upon substantiating a right for the lessee. Such a right is not substantiated by merely renting a place of residence or a place of work, even if it is leased for a long period, nor is it substantiated by the type of work or business or the character of the lessee, which may cause an increase in the value or the demand of the leased area.
This is regardless of whether the common understanding or the governmental laws consider the lessee to reserve a right. It will not be consequential in this case. Hence, upon the completion of the lease period, it is forbidden upon the lessee to exercise any discretion over the leased item itself, and any control that he exercises over the item itself or its profits will be considered a discretion of hostility and liability. In addition, renting out the property itself will be un-commissioned, and will be void without the consent of the owner.
It is possible to substantiate a right according to the shari’a by stipulating a legal conditional. For example, they may stipulate within the lease agreement—regardless of whether the lessor receives payment for the condition or not—that upon the completion of the lease period, the lessor will lease the area to the lessee or a person appointed by the lessee for the same amount. The same will apply to every lessee who has been appointed by the previous lessee.
In this case, owing to the rights afforded by these conditions, the lessee can choose to take the key money and vacate the place, and the lessor, owing to his duty to fulfill the condition (stipulated in the lease), does not have the right to refuse to lease the property to the principal lessee, or someone appointed by him, or any lessee appointed by the previous lessee.

2878. If it has been stipulated within the lease agreement that the lessee may retain the leased area for as long as he likes by renewing the lease for the same amount, then he may acquire key money in return for vacating the place, even though the lessor is not mandated to lease the place to the one who pays the key money.