Tenant Registered Company Question

Sirs,

I wondered if you could help me with something?

My tenant has asked if they can register a company at the address of the property they let from me; is there anything I should be asking them other than “A company doing what?”? I have never been asked this before and I am assuming I would need to speak to my mortgage company also if the tenant plans on running their business from the property too?

Thanks very much in advance.

Yours faithfully

Mrs J Joseph