How long can we keep using M-color?

Hi, there is no actual limit. However, M-Files does not produce any updates to the product anymore so if there is the end of life notice for M-Color which explains that the final version of M-Color provides direct support for Autocad 2023, which after there is no product updates available. 

https://m-files.my.site.com/s/article/M-Color-End-of-Life-Announcement

So until the integration fails by changes in Autocad, it will work.