Having spare dell memory and mac memory for any upgrades

I am having a hard time with those original branded memory modules such as Mac memory or even the more common Dell memory as they seem to have some issues always with regards to compatibility with other laptops as I don’t know if they were built to be just for their own brands of computer. That is the reason I always have to have a stock of these modules just in case I am tasked for a memory upgrade by clients as they sometimes prove tricky to upgrade especially if these are original computers. I make sure to buy from www.memoryupgrade.pro for my stocks as this is the only site I rely on in terms of availability of the said modules and I have done so for the longest time now, I think about 2 years and going for more in the future.