Hi,
To answer your question, first confirm what your iTunes/Music library content consists of:
- Purchased Content: content purchased from the iTunes Store and tied to your Apple ID. Purchased content may be accessed on all eligible devices that are signed in with the same Apple ID regardless of iTunes Match or Apple Music Subscriptions. If you enable Automatic Downloads on all of your devices, once a purchase has been made on a certain device, it generates the download for that content on every other device as well, automatically.
https://support.apple.com/guide/music/buy-or-download-music-mus14076f9d/1.2/mac/12.0?
- Apple Music Content: content downloaded with an active Apple Music subscription and saved to the iCloud Music Library/‘Sync Library’ tied to your Apple ID. This content will only ever remain accessible as long as the subscription stays active. If ever cancelled, all previously downloaded content will disappear from all devices. Purchased Content is not included with this content, nor is it affected by it. If all devices are signed in with the same Apple ID and have Sync Library enabled, the content will automatically appear across all devices. If content is deleted on one device, it deletes across all. Any time you sign in with your Apple ID to a new device, all of your Apple Music content automatically appears available for download. iTunes Match uses the same platform, the iCloud Music Library, to store the matched content. Having both subscriptions, or one subscription vs the other does not matter and is not a requirement.
Turn on Sync Library with Apple Music
- Imported Content: content that has been imported, downloaded, burned etc from outside sources and added into your iTunes Library. Normally, when this content is added to your Library, due to not being purchased from Apple or tied to an Apple Services Subscription, you would have to sync the content from your Library to the affected device. iTunes Match was created in order to avoid that process, and allow for users to access their content on any device signed in with their Apple ID by using the iCloud Music Library, just like Apple Music. Apple matches the imported content to content offered within the iTunes Store, and then uploads the content using iCML. Now, each time you sign into your Apple ID on a device, with sync library enabled, the content will automatically appear across all devices signed in. This avoids the user having to manually sync each device to the Mac/PC the content was originally added to. Purchased content is not tied to or affected by this content and neither is Apple Music.
Subscribe to iTunes Match
Apple Music and iTunes Match are similar, being that they both use the iCloud Music Library/‘Sync Library’, which enables the user to access all of their downloaded content across all devices when signed into the same Apple ID.
However, that is the only similarity the two services share.
Determine what your current Library content consists of. This will confirm which service you will need moving forward.
You should only have iTunes Match if you have content within your iTunes Library that has been added from outside sources, imported, burned, etc, and if you wish to have the ability to have that content uploaded into the cloud to appear on all devices signed in with your Apple ID.
If you do not have any of the referenced content types above, and your Library only includes content downloaded from your active Apple Music subscription, I would recommend cancelling iTunes Match.
If you have the referenced content types above stored in your Library with iTunes Match, as well as Apple Music downloads, I would recommend keeping both subscriptions.
Hope this helps.