What can and cannot start a charge
Reading this site, comparing the four options and completing the health questionnaire all cost nothing. A charge can begin only after a provider has prescribed and you have authorised payment, and the whole monthly price is shown to you before that point.
If you have a prescribed plan
The billing frequency, the cancellation method and the notice period for a prescribed plan are set out with the plan itself, before you authorise payment. Those terms are the ones that apply. Do not read a cancellation right, a deadline or an exception into the educational pages or the published prices.
If you want to stop
Email hello@solenarx.com with the subject Billing question and say what you want stopped. A person answers, and the plan documentation tells you the effective date.
Clinical questions about stopping
Whether to stop a medicine, and how, is a clinical question rather than a billing one. Both finasteride and minoxidil hold their effect only while you take them. Raise it with a provider in the questionnaire thread rather than by email.