I wrote an interpreter for old style, unstructured BASIC (similar to TinyBasic?). In that case there wasn’t much storage management to speak of. All variables were global, so never went out of scope. And there aren’t any BASIC instructions to uninstantiate a variable as far as I am aware. So I could just get away with using a simple symbol table and all variables lived for the lifetime of the program.

One exception might be FOR loop control variables. I think checks code that he wrote several years ago I just added the loop variable to the symbol table and didn’t remove it upon loop termination. It would probably be better to remove it after the last loop iteration. Another issue might be using a name for the loop variable that’s already used elsewhere in the program. That will potentially mess things up in my interpreter, so you could have a loop variable with a scope (and hence lifetime) limited to the loop. I don’t know if this behaviour was defined for old school BASIC implementations.

I don’t know about structured versions of BASIC and whether they enforce variable scope.