One of the fixes to (IIRC 1.5) the game is for memory leak, which would gradually use more virtual memory, but 'dows should page out unused pages into the swap file, so it's not really 'chewing up RAM'. The game can only release that VM when it exits.
In general the RAM use would be asymptopic, rising fast initially then reaching a plateau slowly, with increase only due to 'leaks' where memory is grabbed and not freed correctly.
Most programs stabilise with a smaller working set of pages in RAM, than their apparent Virtual Memory requirements, which is the reason M$ recommend using swap files.
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