Ram for Mac book pro mid 2009 13”

RAM vendors recommend NON-ECC RAM:

https://eshop.macsales.com/item/OWC/8566DDR3S8GP/

A 2009 MacBook Pro can use up to 8GB RAM.

However, if your computer is slow, it is unlikely that increasing RAM will make much difference. Most "slow" reports here are due to old mechanically hard drives note a lack of RAM.

The other responder may think you were asking about a MacPro, a very different computer that uses ECC RAM

Yes you can use.I think the majority of the reason why Mac Pros continue to use ECC RAM is that Apple goes by Intel specifications on reference designs and Xeon workstation/server boards have historically specified ECC memory modules. Someone else can probably elaborate on that.

Just keep in mind that you can't mix ECC and non-ECC modules. If you decide to to go non-ECC, you'll have to pull the ECC ones out.