Users have obtained, purchased different operating systems to upgrade their machines all the times.  There is nothing to worry about.  You can also upgrade your machine to Windows 10 64-bit and Microsoft will give it a digital license.  Dell still supports Win 10 drivers for this machine.
Hello Community, Yesterday I bought the Dell OptiPlex 3010 from eBay and I wanted to restore this computer back to its original operating system which is Windows 7 Pro, but when I ran Dell OS Recovery Tool, my only option was Windows 7 Pro 32-bit. This system has 8GB of RAM and I noticed that the 32-bit version could only utilise half of it. I thought that since my Dell OptiPlex 3020 through Dell OS Recovery Tool could be restored back to Windows 7 Pro 64-bit and I thought there can't be any harm in installing the same OS with the same edition but with the 64-bit architecture. The system activated perfectly fine and the OS runs with no problems. Should I be worried about getting in trouble for this and should have I done this another way? Thank you.
Dell OptiPlex 3010: Concerned about installing Win 7 Pro 64-bit instead of 
using 32-bit