Are there any discounts/sales/etc. on MultiMarkdown Composer?
MultiMarkdown Composer v4 is free to download from the App Store, and then offers upgrades to add additional features. Composer will tell you when you attempt to access a feature that requires an upgrade. More information about the Pro Upgrade is available here.
Whenever you launch Composer, it attempts to check the App Store to see what the upgrades currently cost. If the price is lower than seen previously, you should be notified that the upgrades are on sale. I can't guarantee that this will work all the time, so I recommend keeping an eye on Twitter (@MMDSoftware), as well as our mailing list.
If you previously owned v2 of MultiMarkdown Composer, there will be a release of v4.0 that will work for you. You will not be able to upgrade it to the Pro version, and it will not include future updates after 4.0. It does allow you to use the new version and new features, however.
After 4.0 is available in the App Store for purchase, there will be a discount to allow owners of v2 to upgrade for a reduced price. I don't know exactly when that will be, but it will be announced on Twitter and the mailing list as above.
UPDATE: The discount period was announced yesterday (Sep 18, 2017) -- due to some of the App Store issues with launch, I wanted to go ahead and offer a discount both for old users and as an apology for the issues going on. It will run at least through end of day Sep 20 (Eastern Time).
I will offer periodic sales in the future.