tradertefI run multiple $10K MRR companies on a $20/month tech stack
https://stevehanov.ca/blog/how-i-run-multiple-10k-mrr-companies-on-a-20month-tech-stack
There are zero reasons to limit yourself to 1GB of RAM. By paying $20 instead of $5 you can get at least 8gb of RAM. You can use it for caches or a database that supports concurrent writes. The $15 difference won’t make any financial difference if you are trying to run a small business.
Thinking about on how to fit everything on a $5 VPS does not help your business.
$15 is not exactly zero, is it? If you don't need more than 1GB, why pay anything for more than 1GB?
I recall running LAMP stacks on something like 128MB about 20 years ago and not really having problems with memory. Most current website backends are not really much more complicated than they were back then if you don't haul in bloat.
Given how much revenue depends on the experience of a web app and loading times, I’d be happy to pay 100$ a month on that revenue if I don’t have to sacrifice a second of additional loading time no matter how clever I was optimizing it.