Provenance, having a chain of receipts, documenting identity and ownership. In plants you need to document that the DNA is identical. That it is a clone, or you can not get the added value price. Not just by comparing pretty pictures from a golden book.
I know from what you have said I will be reluctant to purchase named cultivars from your nursery because you do not understand the importance of provenance. It is similar to pedigree papers with dog or horse breeders. Just because it looks like a certain breed, without the AKC or similar papers, you can not get pedigree prices. Pound puppy prices unless you can clearly demonstrate provenance.
If you are planning to start a part time or full time nursery operation, you NEED to save every receipts and the original plant tags for your purchases of propagation stock, so you can document to customers that the names for your cultivars are accurate and not just pulled out of your hat or invented. Comparing pictures to determine what cultivar you are looking at is a fail.
With my orchid collection of select cultivars, I had brass numbered tags tied to the rhizomes of my more valuable clones, so that if they got knocked out of the pot, and the plastic tag got lost or faded, the stamped number tag was tied to the roots. Here a "normal" Paph rothschildlianum from seed might be worth $75 to $150 at blooming size. A blooming size division of an awarded Paph rothschildianum 'Mount Milais' FCC/AOS might sell for $1500 to $4000 depending on how recent the award. The most I ever sold a single orchid for was $2500. The person who bought it, made his investment back with interest in about 5 years. Here provenance counts, pictures are important, but a chain of evidence, receipts, plant labels from source nursery, who you got it from, what is the parentage and the history, is all critical. And these are windowsill size plants.
With trees, similar care must be taken. Keep fresh legible labels on all trees you plan to eventually propagate. Otherwise your collection will become a bunch of worthless junk, that can only be sold at the no name seedling price.