I keep working in this project, i just want to ask about take commercial photos inside someone else business.

My model will sign the release papers, so no big issue now with it (this was my original question some weeks ago (link to original post: https://www.microstockgroup.com/general-stock-discussion/question-about-papers-to-fill-from-models/).

I am worry about legal issues, my nightmare will be to finish and publish my book and get some claim for some possible mistake.

I was planing to take the pics inside a gym, i am not the owner of the gym and i am worry about some kind of futuer claim for using someone else place; i totally don't know how it works.

My question is: did i need some kind of paper or specific document to take and use these pics for commercial use??

You should get a property release from the owner of the gym. You should find that easier to arrange because you can be very specific about what the images will be used for (unless you're also going to submit the pics as stock, then just use your agency's official property release. Someone more knowledgeable than me will be able to tell you whether you also need releases from the manufacturer of any gym equipment which might be visible/identifiable in your image/s. I'm pretty sure you would for stock, if they are recogniseably distinctive.

I catch it.

Did i still need the property release if i totally photoshop the background of the pic??

If you can't see the property in question - either because of a shallow depth of field, how you framed the photo or because you replaced the background, then no,  you don't need a property release. The release relates to what's shown in the image and if it's not shown, then there's nothing to need a release.

This photo, as an example, could have been shot anywhere, so I didn't provide a property release and no agency has ever asked for one

https://stock.adobe.com/images/joys-of-gardening-pruning-the-azaleas/131420021

This one was on private property I didn't have a release for, but was framed so it didn't become an issue

https://stock.adobe.com/images/young-girl-enjoying-a-boat-ride-leaning-out-for-a-better-view/131610755

This one needed and has a property release as well as model releases, but if the fire and wall were photoshopped in, then you'd be fine with just the model releases

https://stock.adobe.com/images/family-by-the-fire/130685183

Does that make it more clear?

Thank you so much for your feedback, no i get the whole picture about this issue