What is the ruling on purchasing an advertising service that grants the advertiser a share of the website's profits for 55 days, with the profits ceasing upon reaching 10% of the service's value before the end of the agreed-upon period?

What is mentioned in the question indicates that the true nature of the transaction is that the participant paid fifty dollars to receive fifty-five dollars in return, under the guise of a "partnership," which it is not. The essence of contracts lies in their meanings, not their wordings, and dealing in this manner must be avoided.