What John said. Just one small caveat: Unfortunately, soundpools are *not* covered by this activation mechanism for practical, logistical reasons. 😭

This is what happens when you enter an older Music Maker or (Samplitude) Music Studio serial number into a current Music Maker version that uses the in-app store system: The program sends the serial number to the server, checks what product/version/edition it is, and whether that serial number is actually registered to you. (It needs to be under the same account as the one you're using to log into the in-app store system.) Once this first part is done, it uses a table on the in-app store server to look up which particular feature and software instrument items were associated with your particular old program version, and credits the matching in-app store items to your in-app store account, so those become available to you in the current generations of Music Maker. This is essentially a workaround solution to bridge the gap between the old copy-protection/DRM system (i.e. "Protein") and the new one (i.e. in-app store).

Here's the problem with soundpools: Not nearly all of the soundpools included with old Music Maker versions are available as in-app store items in that shape and form. So, for many of them there is no matching soundpool that could be credited to you via the store for owning an older version. If you want to use those soundpools from your older versions, you have to get them from the older version. At least for the disc versions, this should be fairly hassle-free, as the soundpool folders are located in a sub folder of the program disc, and can simply be copied from there to your hard drive, without the need for the installation of the entire program.