"Ashampoo will not doubt keep sending reminders or special offers, very similar to Serif."
I have a number of Ashampoo freeware and Serif paid for programmes and I can confirm what spuds said and tell you that things haven't changed in that respect. But it's no big deal to delete those emails.
If you register with them, everytime you download one of their programmes wether or not you buy it. You get the same treatment that a purchaser gets. All their software have 'License Keys' and as a registered user you will have a personal Accounts page, where all the software you've got from then and all their registration keys are kept. Should your PC have any sort of trouble, such as a HD crash or loses all your software. You can just sign in to Ashampoo, go to your Acc page download the software again and pick up your license key.