Do i need to pay every month or every three months to LSP's? Or is it just a one time payment?
Those fees are paid to LSPs, and they are tied to on-chain fees.
Feel free to check out https://mempool.space/ for current on-chain fee rates.
Best,
JP
Discussion
You only pay that fee once to open the channel to the LSP and then can use the channel until it is closed. I have been using Alby Hub for a few months and not had any channels closed on me.
There are a variety of reasons a channel could be closed and you can get some info here: