Your pricing model seems very strange. I recommend that you change your pricing so that you offer a package which is a monthly fee (and can be even tiered, so that you can charge for additional features).

For example, your service is similar to a service offered by ADT alarms in the UK; http://www.adt.co.uk/tv?ppc=aa-C1-bb&campaign=burglar_al...

As you can see their pricing structure is more expensive then yours and this is a good thing as users, can see real value from the service - especially with a higher price associated to it. The reason I say this is a good thing is because, I believe that you are pricing your product to cheaply and as a result people may not see value in it which is why I think you should consider actually increasing the prices you offer

For instance, I think people would be prepared to pay the monthly figure (or even more) for "peace of mind" that their homes are safe when they are on vacation.

You should use A/B testing on your pricing model to see which is the perfect price point for your product but currently it seems very low and makes me think as a user "is it really useful?"

Additionally, you should contact insurance companies and find out if users use this service, will it benefit their insurance premiums etc because, if it does then you can definitely advertise this as a bonus of using your product.