How to handle a use case with many dormant process instances

I’ve this workflow with many dormant process instances waiting for user input for months.
The process instances can be thousands.
I’m wondering if all these instances will consume too much resources: are they consuming just database space or they have also memory impact?
There’s a guideline or best practice to deal with this use case? It’s better to schedule these process instances to go in a termination / end state after some time or camunda can happily live with all these instances?

Kind Regards,