You can make a deal with instantaneous effects but long term consequences.
when casting this spell the target must be willing. You can make this transaction by shaking the other being’s hand (during this your hand will be surrounded in cold fire with the color of your choice if it’s a soul contract) or summoning a contract (which must be signed in blood or squid ink is it’s a soul contract) that will burn up at midnight if not signed. The target must know what they revive out of this transaction and what you will receive.
Items: if you make a contract where you revive items the contract is completed once you and the target both receive what you bargained for.
Services: if you make a contract where providing services is involved the contract ends when both parties have completed their obligation.
Souls: if you make a bargain for a being’s soul then may the gods help them. Once you hold up your end of the bargain you basically own their lives. You could kill them in a whim, cast spells on and communicate with them through their contract. Soul contracts are especially powerful because they can have magical effects such as: raise or reanimate the dead, polymorph your target, make someone a warlock with you as their patron, increase any stat by a permanent +5 or -5 and create a deadly plague that effects only a specific person or group. If someone dies under a soul contract their soul becomes a lemure which you can promote up until your just before your level using spell slots and these devils can only make deals for you. If your contract is breached by the other party then you can revoke their what they receive and keep their soul. You store the soul in small cubes of magical energy which only you can open and summon at will.