Where have you read this? Don’t assume anyone’s word. Check online for registered trademarks. As far as I know the only valid one is in Germany. It’s easier for apple to just send you this automated letter with no guidance. They will not advise you. You could argue the case but selling this game with this title in Germany is going to be nearly impossible. Now that ravensburger are doing apps they may have updated their trademark for context with software. It’s a tricky one. If you see any record of international trademark using this word post the link as I will be very interested to see this.
It is stated on a few German websites and in the link I posted above. I did not find an international app yet that has not been made with or for Ravensburger. They seem to have control over this “brand” all over the world.
I asked the review team:
Can we use the word “memory” (lowercase) ?
If not, is “Memory!” or “memory!” allowed ?
Apple
Sep 25, 2013 07:22 AM
Thank you for your response.
It would be appropriate to remove “Memory” or “memory” from the name of the app.
Kind regards,
App Review Team
Now what?
Is “Memory!” allowed or not, not sure from their answer…
I don´t think that any form of “Memory” is allowed… 
How about “Speicher”
Someone should trademark that one out of spite! :)
Sure just build a brand and you may own the rights for this word in 40 years 
I had the same problem with an app of mine a little over a year back. I just changed the name back them. It also contained the word Memory in the title.