I've heard about ways you can keep a spirit or entity. I'm not sure how that sounds to me it sounds like slavery, I don't believe spirits should be kept but then again I don't much about it. There's these sites online like Creepy Hollows and others that sell spirits and such but I don't know if they're just scams or not. It seems like a lot of people are spirit keeping though from what I've seen Creepy Hollows looks very popular.
It's a scam. I mean think about it, why would a spirit obey you if it is trapped in an item? Even if it isn't trapped and is free to come and go, why would it help you? And what spirit would agree to that? And if it worked, don't you think everyone would be using spirits to get ahead in life?
I'm not saying it isn't possible to gain help from spirits but generally it isn't something you can buy. You have to search out a spirit or create one (fetch/thought form) and start a personal relationship with it.
When it comes to any online site using spirits, witchcraft, divination or any occult practice...use your common sense.
Creepy Hollows is a questionable place, but binding spirits is a very real practice.
As for whether it is slavery, it depends on the type of binding, the extent of the binding, and the nature of the spirit. There are spirits out there with very limited sentience, and some that are non-sapient.
While it is indeed possible to do something as sordid as take a dead old man's soul, bind it, and practically make him into a slave, it is also possible to take an abstract un-personified force, like a pattern, and create a talisman, with its energy imbued which acts as a gateway to that energy. This is less ''binding'' and more of a linking.
Now in between those two, you'll find a whole range of binding magics. Some are non-sapient and wild entities, much like animals, being bound in the same way that we keep pets, because the alternative is being destroyed by them. Some are egregores, wild thoughtforms with as much ''personhood'' as weak AI, and some may be very very harmful to humans, and a simple banishing would not do the job.
Suffice to say if you can bind humans, you can bind spirits. If you can enslave humans, you can enslave spirits.
As for the questions IrisMoon put forth:
1. The item is a vessel of manifestation, the binding lies behind the physical effigy it is bound to, and it's the spiritual bondage that forces obedience and constraint.
2. Depends on the spirit. Most entities don't need to be bound to help you, and in my experiences, a friendly and free relationship is best. The main reason I oppose things like the Lesser Key of Solomon is because of that. If the item is nothing more than a link to the spirit's energy, or current, then you have your answer there, it's an aid for the magician to connect to it.
3. If it is just a linking type of thing, almost every spirit would agree to do that, to have another vessel and gateway of manifestation here. If it is a forceful, slavery-type binding, however, I don't think any entities with sentience would agree to that. Thus, the binding is forceful. Depending on your ethics that may or may not be something you're comfortable with. Others, aren't even sentient. Some are much like computers, having limited consciousness and doing the thing they're programmed to do.
4.Not really. Everyone can use magic to get ahead in life, yet most people don't seem to be actively and consciously using it, though they are nonetheless applying it indirectly. There is also the fact that we are not exactly living in a pro-magic world nowadays.
I took another quick look at 'Spirit Keeping'a guide for spirit keepers.
In a nutshell...your not binding/enslaving a spirit to anyone or vessel.the simplest way to explain it is...your exchanging names,phone numbers and address' or like creating a short cut icon on you're computer screen.so when you need them,they're there immediately.so they can find you at the drop of a hat.
Your creating a permanate or temporary bond with them.and a spirit can freely agree to it or not.so it could take awhile to find a spirit to bond with.
Hope this helps to clarify.
I've never done it myself.haven't seen a point to it yet.