Is it permissible for a website to lease advertising space without specifying a duration, and is it permissible for the rent to be variable based on the number of clicks on the advertisement (e.g., one riyal per click)?

It is permissible to rent a space for website advertisements, provided that the content of those websites is not forbidden, while taking into account the abandonment of what is forbidden.

As for the rental period, it must be known. It is permissible to agree on a daily or monthly rent without specifying an end to the period.

Regarding renting based on the number of clicks on the advertisement, there is no harm in it, provided that a price for each click is agreed upon, and that it does not lead to an increase in the number of visitors by using a program or hiring someone to do so. The uncertainty of the number of visitors does not affect the validity of the contract, because the outcome of uncertainty leads to knowledge. If the number of clicks is falsified, then that is a sin and unlawful gain.