I'm also somewhat confused regarding API - thingy .
You mention that depending on usage
GG API can be withdrawn ( Sounds a bit scary if you do client work )
I need to understand is there any hints when this would happen ?
I have been using GoThru previously for my Street View work - never any API warnings there.
Some of my restaurants I shot earlier have hundreds of thousands of views.
Would that affect your bill for API usage ?
or does it happen only for embedded tours ?
I shoot Street View more seldom now and have a small 4 node project that I guess could have 1000 views a week .
I thought that would be a perfect time to test Pano2 VR

Do i need to mess with my own API ?
I also could use Street View app on my iPhone for those 4 images.
why on earth I don't need any API using that ?
browsing this topic on some FB groups feels like opening a can of worms .....