Your Paypal account will have all your purchases that you paid* that way indefinitely.
Personally, I record all my purchases and sales in a notebook, but I am old and set in my ways.
*If you are using Paypal, and it is a useful service, back your account with a credit card. Then if you miss the 45 day deadline for a PP or eBay dispute, you can go to the card's chargeback service, which has a longer deadline.
If your item is late, and coming from Asia, do NOT allow the seller to promise a replacement. It won't arrive and the original may never have existed. If your item does not arrive within 30 days, 40 at most, open a Dispute and get money back. If the item arrives later, you can refund the refund by using PP's Send Money service.