I enabled STP for one company, but the company didn't use the subscription and no employee was paid. Can I change this subscription for another company?

Hi angelayu619, 

Thank you for reaching out on this.

I would suggest using a different subscription for another company as while you were enabling the STP for the other company, the Business Management Software (BMS) ID would also have been registered with the ATO. 

Hope this helps. 

Thank you and please let us know if you require any additional assistance.