How can I know if my MacBook pro supports 8 gb or not? Here is my serial number:
This is your mac: http://support.apple.com/kb/SP544

4GB (two 2GB SO-DIMMs) of 1066MHz DDR3 memory; two SO-DIMM slots support up to 8GB

A cool trick in case you want to find more about it is you can type your serial number right into the support search on the apple site and it will bring up your model and specification article. Take a look: http://support.apple.com/specs/#w89253hx64c