Besides, one generally cannot upgrade a laptop. Add a memory stick perhaps, seeing how you only have one and the memory operates in a single channel mode. But that would not help with stability anyway, and visibly improve performance is specific cases only.
It’s most likely due to outdated software / unstable OS. A fresh OS install might be needed if you’re not tech-savvy enough to salvage what you have now; in which case it’s not the right forum to ask a question like this.
Start with video adapter drivers, then use a tool that cleans up odd bits & bobs - like CCleaner, and run chkdsk and / or memtest if the crashes are truly random and sporadic.