Hi,
So the truth is, it will be hard to get people to sign contracts after purchase so the best thing may be to use a beat cart like the ones offered by
myflashstore or beatstars which will allow you to create a contract and attach it to every transaction. (I think they append the buyers name to the contract as well)
IMO, this might not really hold up legally as there is a bunch of holes in using this method - but it does serve as a purchase receipt which does offer some additional comfort for both parties about the transaction so...it is what it is..
There are a few e-sign services out there and i believe most have either a charge per transaction or a monthly fee so its probably best to just google them and then check them out one by one and see which one is going to work the best for you.
Regarding split sheets:
Speaking from my experience (I've been successfully selling beats online & on SC for a few years now), you can try but It might be more headache than its worth - especially with leases.
Also, most artists that buy beats online assume that an Exclusive license purchase is royalty free so you will probably have some work in front of you if you want to do a split. In an ideal situation a split sheet is somewhat of a given - but when it comes to selling beats online - split sheets are....
so - it may be more headache than its worth.
Take it as you will.
Good luck.