Create a Versatile Login for websites, which allows exploring more options for online service clients:
for example, that they can buy a monthly or annual membership, and that this is a condition for whether they can schedule in the calendar, in addition to the versatility of being able to make consumables, that is, following the example, I buy 5 medical consultations, which validates whether I have available consultations, and that each time I schedule my consultation, 1 is spent until there are 0 left and I can buy more.