How do you store sealed promo cards without damaging them?

Recently, I finished my 151 master set and am now aiming to collect all the promos. I have a lot of sealed promo cards that I’ve kept in my binder by folding the long plastic flap, but I recently learned that this could potentially cause damage over time.

I still want to include them in my binder, but I’m not sure what the best practice is. How do you store sealed promo cards? Is folding the wrapper okay? Will the crease eventually become visible on the card after a few years, or should I be concerned?

Any help is appreciated, thanks!