In my humble opinion, I'd stop now. Saying "after this month" implies you're going to use it anyway until it's gone.
Frankly just bin it and accept the small deficeit your finances incurred. If the product is not worth continuing with beyond this month, it's not worth continuing with now. Another 3-4 weeks, won't suddenly make it a better product. We are after all, talking about some god awful detox product here, not grass fed beef.
You deserve better than to persevere with such worthless products, because you're worth more than that. Much much more