Making proprietary code accessible but not downloadable

Question

For historical and legal reasons (industry funding and contracts), we have proprietary simulation code (that we wrote, some in C and some in python) that we can't make publicly accessible.

However, we want to preliminarily move to a model where at least the functionality of the code is more accessible. I know one model people use is to have people submit jobs to our servers, and we just return results.

However, is there a way where people we've granted access to can use the software on our computing cluster, but not take it with them, e.g. at least in a sandboxed environment so that they may use/debug their use of the code before submitting jobs to the server? Does C/python code make any difference.

I know ideally we'd just make the code open source and not worry about this, but (out of my paygrade) this is not in the cards right now.

Apologies if this question has been asked or if it is super basic -- I'm not sure what the right terminology to use and search with to address this issue.

Thanks!