Historically Tesla owners have paid about $2,000 per vehicle (included in the purchase price) to further the development of the Tesla charging network. That, among other things, is why Tesla vehicles tend to be priced more that other EV's which have no investment at all in a charging network for their vehicles.
Due to this, a world wide network of private charging stations has sprung up, and is financially supported by a fee paid by every person plugging in and are usually charged per minute, or per kilowatt used.
If you plug into the TESLA network you will be free riding on their investment. If you ask, you may be given permission to plug in your leaf, however they would have no obligation to allow you access.
Some higher end enterprises have also requested Tesla charging capabilities and do so as they wish to attract the more well to do Tesla clientele. Again, you may request to tap into their network, but if possible you should avail yourself of a blink or other such commercial charging location.