Say that I put in my application, windows version, mac version is on MAS, and have it for sale by Kage or Fastspring; do I need to generate license numbers?
Your app must handle the validation of serial numbers/keys. Fastspring has multiple options for delivery. You can upload a pre-made list of keys, or give them access to a key generator (either by calling your server, or sharing the code with them) and they will deliver it for you. I don’t think either Kagi or Fastspring offer a drop-in DRM lock.
By the way if you offer purchase of the Windows version (inherently outside the Mac App Store), be sure to include a way to buy the Mac version outside of the app store. I’m sure I’m not the only one who favors apps outside the app store.
Did not consider that. There are something in the Win version not in the Mac version because of Sandboxing. Need to re-think that.
Tim, do you use Fastspring? If so are you happy with their service? I have been giving them a good look. I used Kagi wayback when.
How do you do license, what do you recommend? Currently I’m not doing any license keys.
I was seriously considering Fastspring prior to launch. In the end I wrote my own little shop because I have an understanding of PHP.
A consideration to take is the quantity of sales, as this would determine how complex of a system you’ll need. Should sales be relatively low, you may not need the most complex of systems and might not need a sales gateway. Where on the other hand, if you have a consistently high number of sales having a third party manage payments might be incredibly useful.
Next consider how much work you want to put into licensing.
If you want a simple system where you don’t even have to worry about keys, selling MAS only is the way to go (at a 30% loss)
If you’d like someone to handle sales, refunds, chargebacks, issuing licenses, and more a third party with tools already made would prove beneficial. Fastspring offers a lot of great tracking tools, and they will work with you one on one to set up your shop which I thought was really cool. And while a third party seller would not take 30% of your sale, they still take a larger cut than doing it yourself.
Should you feel comfortable enough to handle it on your own, you can maximize the amount you keep by setting up your own shop and process with PayPal or Stripe. This method will put you in charge of everything though. That can be good or bad depending on how much control you wanted to have.
Paddle reached out to me after I sent out a press release for the Answers launch, but I haven’t investigated their options.
Also consider your target audience. I believe you write the RV apps, correct? I haven’t dabbled in that area, so I’m not aware of your levels of piracy. But allow me to tell you about a past experience of mine.
I wrote an app called MacDust. It cleaned out files and internet history and such. There are plenty of legitimate uses for that, especially in 2007 when disk space wasn’t so freely available. However, a large amount of users were pirates covering their tracks. I understood this, so I made sure not to spend too much effort on trying to lock them out, since they were going to get in eventually. I decided my best defense was to make the key validator inside the early versions deliberately vague. Pirates guessed on key formats that worked, but they weren’t to the specifications that legitimate licenses would fit. So each version I could make the validator slightly more strict and it would slow the pirates down for a version or two without affecting my customers.
So how much effort do you need to put in to stop piracy? Is your app going to be high-profile among pirates?
Quick Overview
App Store - No need to worry about keys; 30% loss.
Fastspring - Incredible tools and great support, you need to create keys; 8%ish loss
Selfie - You’re in charge of everything; 1%ish loss (transaction fees)
[h]In short[/h], I really can’t recommend a solution to you - it’s a highly personal choice. I’m happy to try to give you help deciding your path, but it’s not an exact science 
Also the shop for Answers is secretly quite complex. It tracks transactions and abandonments, has support for coupons, recovers licenses, permalink receipts, and other neat things. Take a look at it, I’m really proud of it 
While I encourage you to check out and buy Answers, I can also show you the process start to finish of the customer experience. I spent about three weeks on the website as a whole, two weeks of which went into the shop.
In the Mac App Store you will not be able to have license numbers, since you never have direct contact with the customer, unless he comes to you for support.
With Windows, all depends whether your app requires a license number and what you want to do with it. If you actually use the license number to do something, like tracking updates and offer extra support, fine. License numbers are good for apps that require a lot of support, so you avoid supporting pirates. They can also be used to try and sell upgrades. If no such things, don’t bother. It does not mean you will not be able to track customers. I personally do not use license number, but track customers by their Paypal transaction number.
For my self I’ve decided not to use any other Services for my Windows Apps than just Paypal. After transaction ist done I send an AES encrypted license file via email, which can be drag & dropped by the user easily into the software unlocking a prior demo version to a licensed full version. That’s the best user experience I would suggest for myself and you can transport more information that just a serial number like service level agreements or terminating dates.
Some screenshots how this looks like can be found here.
If you don’t have license number how do you control the user paying upgrade price vs full price?
As I wrote, if you want to do upgrades, then the license number can be necessary.
Sorry, miss that.
I could do something similar, use the sale/invoice number. I think that would work. I hate serial numbers about as much as I do passwords.
Thanks all.