Do I have to pay Rs 50 subscription fees even in a month where I have not done any Direct MF transaction?

I intend to invest in direct mutual funds only 3 - 4 times in a year. So, do I have to pay the subscription fees of Rs 50 even in the months when I am not buying any Direct MF?

Coin allows you to invest for free upto Rs.25k. If you cross the free limit of 25k, then you will be charged a Coin Subscription fee of Rs.50/month which is independent of the number of mutual funds you buy, independent of the number of mutual funds you redeem and independent of your investment plan(SIP or lump sum). So yes, if you Coin investments exceed 25k, then you will be charged Rs.50/month.

Will Zerodha charge rs 50 every month for SIP installments or that will be for one time when I make fresh investment.

This is answered in the link below:

I want to invest through Coin in direct MF. I just want to know how much I shall be charged if I have 3 different fund and investment in each fund is Rs 30,000/- i.e total investment is Rs 60,000/- in 1st year.

Shall I be charged for each fund @Rs 50 pm for excess of Rs 25,000? Please clarify.

You will be charged Only Rs.50/- per month when you cross limit of Rs.25000/-
( No matter how many mutual funds you hold you will be charged Rs.50/- per month only )

I want to know how to invest in zerodha coin and how to buy MF and Charges to Start Zerodha Coin