We do recommend cleaning your Rocketbook pages every month or so, and there can be some light staining on pages when ink has been down for a long while. However, it's expected that a page designed to plan things out up to a year in advance will be cleaned a bit less often than that.
For most cases, some hot water and a good thorough cleaning with the provided microfiber cloth should take most of it up. Additionally, it's worth noting that any staining that might occur will not affect writing, so you can continue to use that section for years to come.
Should you find this at all debilitating to your writing experience, please reach out to us at hello@getrocketbook.