Tenants Overworking Washer , How would you handle this?

[Bob Romano]

How would you handle this situation: 

My Tenants own a commercial cleaning company. They have been in since Oct 2019, always pay on time, no issues there. However,  I was at the house yesterday to inspect an issue they had with the furnace and I noticed that in her new washing machine ( that I supplied) she had a bunch of towels, mop heads and cleaning cloths she uses in her commercial business. Now i don't feel that she should be using the house washer for her business because it wasn't designed for that and it's only a matter of time the machine is going to break and i know she is going to be calling me to fix it. 

What would you do to mitigate a foreseeable problem ahead?