What is the ruling on working on a digital project for electronic sales confirmation in exchange for a specific profit percentage on each transaction, given that there are levels requiring increased capital and inviting friends, and is it permissible to suffice with the first level without inviting friends?

Paying a subscription for "electronic sales confirmation" is forbidden because it is gambling, as one pays money hoping to get more than what was paid. This is known as "guaranteed loss and probable gain." This was affirmed by Al-Bujairmi and Ibn Uthaymeen in their definition of gambling and maysir (definition). Furthermore, this transaction is not a permissible investment because it does not meet the conditions of legitimate investment, such as the field being permissible, the capital not being guaranteed, and the profit being specified as a percentage of the actual profit, not the capital. If the capital is not returned, it is gambling; if it is guaranteed, the investment is invalid; and if the profit is not specified as a percentage, the investment is void. Therefore, this transaction is forbidden and must be stopped. Its prohibition is further intensified by inviting others to it.