"I will live on Kronos three years from now."
Translation:wej nem Qo'noS vIDab.
Good question. The canon seems to be inconsistent on this point.
Within the same document ("1999-09" in the klingonska.org canon database; from HolQeD 8:3), we see both «wejnem is "three years from now"» and «The phrase cha' vatlh ben would mean "200 years ago."»
(On the other hand, that might be due to OCR mistakes in scanning the HQ article.)
Compare also the cha' vatlh which I would have expected as cha'vatlh.
Another document, "1999-11-05", has vagh SanID ben for "five thousand years ago", where I would have expected vaghSanIDben or at least vaghSanID ben.
"1996-12-12" has loSmaH ben jIboghpu' as the way to say "I am 40 years old" (i.e. "I was born 40 years ago"), with loSmaH as one word but ben separately.
I think -maH and -Hu' have always been written together with the numeral, but with the bigger units (e.g. SanID and ben), usage seems less uniform, for some reason.
They're actually nouns. But as mizinamo says, they're not spaced consistently.
maH and so on are called "number-forming elements" in TKD and "suffixes" in KGT, so that's not consistent, either. And they've been used independently. vatlh has been used without a number several times. I'm not aware of maH having been used so. Okrand has written both SaD and SanID separated from its number. In paq'batlh, we have the line SaD law’ San chenmmoH qeylIS Kahless decided the fate of thousands and veng HeHDaq lutlha’ SaD law’ nuvpu’ Thousands followed him to the edge of the city. In a message to me he once use the term SaD DIS poH for millennium.
So none of these are really suffixes per se. They're nouns, in the case of the "ago" and "from now" words, and numbers in the case of maH, SaD, and so on. But the numbers aren't exact numbers unless they're counted: SaD means thousand but not one thousand.
And the spacing seems pretty much arbitrary.