Apple are very strict with their guidelines and are not very helpful when it comes to using their Express Lane for support. Fortunately there are work arounds when it comes to issues they can’t help you with. Your Apple ID is used to login to iTunes Match but sometimes things go wrong. For example I changed my email address recently which meant I had to change my Apple ID. iTunes Match then got confused and thought I was trying to use a new Apple ID and it then told me:
You can use iTunes Match on this computer with just one Apple ID every 90 days. You cannot associate this computer with a different Apple ID for 37 days.
If you see this error and you are genuinely not trying to use a different ID then you can easily bypass this by creating a new iTunes library and import your music/movies/apps/books etc into this new library. Now turn iTunes Match on and login with your new Apple ID. No error this time.
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