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.

Or better yet, go with a euro provider like Hetzner and get 8GB of RAM for $10 or so. :)

Even their $5 plan gives 4GB.