In my video below I show you how to upgrade the SSD memory card in your 2012/2013 MacBook Pro with Retina Display. I will insert a disclaimer here stating that if you do decide to upgrade your SSD in your MacBook Pro that you do so at your own risk and I am not responsible if you end up damaging your MacBook Pro.
Thanks to Amazon you can find various SSD upgrade kits for those who are willing to take the risk of doing the upgrade yourself. I will recommend that you do take your MacBook Pro to a certified Apple store to do the upgrade for you.
The SSD card that I swapped out was a 246GB one and I was lucky to find a kit on Amazon that came with a 1TB SSD upgrade card as well as an SSD USB enclosure for my old swapped out 256GB card that I can reuse as a general purpose external hard drive which I thought was pretty cool to have.
If you want to get your hands on one of these kits you can get them from Amazon here. I must stress that you ensure that the kit is compatible with your make and model of MacBook Pro before you make that purchase and I also recommend that you use an ESD (electrostatic discharge) wrist strap when doing the upgrade. This ensures that you do not end up damaging the SSD card by zapping the card with a high voltage spark from your hands.
Checkout my YouTube video below on how to upgrade the SSD in your MacBook Pro, to see this process in more detail. Enjoy!