Hi,
Yes, it is possible to upgrade RAM. It depends on what CPU is in the notebooK
So, if you have a 6th or 7th gen. Intel Core CPU you can upgrade to 16GB (2x8) of DDR4 2400MHz RAM. The RAM will run at 2133MHz.
Ex:
https://it.crucial.com/compatible-upgrade-for/hp---compaq/hp-250-g6-(intel-core-i7-7500u---i5-7200u-...
If you have a Pentium or Celeron CPU you can upgrade to max 8GB of DDR3L 1600MHz RAM (there is one slot)
On page 45 of service manual you can see the steps to install the RAM
http://h10032.www1.hp.com/ctg/Manual/c05485525
You should also consider upgrading to an SSD if you have a regular HDD (mechanical) in the notebook as it would give a good boost in everyday performance.
Hope it helps,
David
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