It's possible to meter it. The problem though is that meters like a Kill-a-Watt tend to fail under extended use at high power.

The car does not have a metering system for each charge.

Better is to estimate using time and cost of power. Charging 12A at 120V is 1.44kW. To get the number of kWh multiply that rate by the number of hours. For example, just to keep it simple, say the charging window is 10 hours. In that 10 hour period 14.4 kWh would be delivered.

Now take that energy and determine the cost. For example, a summer kWh for me is about 12 cents total. So, in that 10 hour power the 14.4 kWh * $0.12 is $1.73. Over the course of a month that's about $52.

Now this example is far from perfect. That 14.4 kwh gives close to 60 miles of range per day (56.2 to be precise at that Bolt's stated efficiency of 3.9 miles/kWh). So, if you average mileage is half that per day, then you're over by double.

So, that leads to likely the best estimator: convert miles per month into cost. Using the numbers above it's possible to determine that the cost per mile driven is $1.73/56.2 which is a shade over 3 cents a mile. So, you can simply record the mileage for a month, multiply that by 3 cents, and pay that. So, if you go 850 miles in a month, pay 850 * 0.03 = $25.50 for the month. If it were me I'd round it up to $30 just to thank the landlord for facilitating charging my Bolt.

Hope this gives you some insight. I strongly suggest not trying to be a stickler to the penny. If you show your landlord some rough estimates, then offer to pay something reasonable in the ballpark of those estimates, you should be able to get this thing done.

ga2500ev