I don't know what anyone sees in ShareIt, to be honest. Plimus and BMT Micro both offer a lot more for a lot less. I ditched ShareIt a long time ago and I see no downside to that decision.
RegNow have a lot of affiliates, but they're very expensive unless you use them as your only payment provider, and they're pretty fiddly to set up. RegNow are perhaps worth using as a secondary provider as they can take PayPal payments for you, without you needing a PayPal account, without the risks FlameDuck will refer to, and without you having to set up some complex scripting to automatically deliver downloads/keys to the users or leave them to wait until you can do it manually.
RegNow have a lot of affiliates, but they're very expensive unless you use them as your only payment provider, and they're pretty fiddly to set up. RegNow are perhaps worth using as a secondary provider as they can take PayPal payments for you, without you needing a PayPal account, without the risks FlameDuck will refer to, and without you having to set up some complex scripting to automatically deliver downloads/keys to the users or leave them to wait until you can do it manually.