How long can I use moss for before I need to change it?

Recently I've been thinking of getting my BP's vivarium some Sphagnum moss to help with the humidity.

I just have a few questions about it and how I should use it:

Do I need to remoisen it? If so how many times should I do it before I need to change the moss? Is it a good idea to change it every time I clean the vivarium (once every 3-4 weeks) or can it go longer?

I would just use your own discretion. We have used it in the past - you have to soak it I would say every 3-5 days depending on your tank style. I just re-used until a next big monthly clean. If you snake were to excrete urates or feces on or near it then I would chuck it. We bought the Zoo Med Terrarium Moss and you really just need a chunk - no need to use up the whole box.