Check the VM settings to ensure that the VM really does have that much memory and doesn't just appear to have it. Make sure the VM host isn't stealing back SQL's memory.
Page life expectancy of 300 is a very old recommendation that was barely valid when SQL usually had less than 4GB of memory, it's a completely incorrect guideline these days being way too low. A server with 200GB with a page life expectancy of 15000 is probably indicated as under severe memory pressure.
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)SQL In The Wild
: Discussions on DB performance with occasional diversions into recoverability
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