You will get ads on Live TV, but if you see them on Catch-Up or Box Sets then you can try the following:
Check you are logged into the STV account you originally signed up with.
You can check which email address you used to sign up to Player+ with by checking the invoice you received from Apple - this will be from the email address : firstname.lastname@example.org and have the subject line : Your invoice from Apple - this will show the email address used under the Apple ID heading.
If you have multiple STV Player accounts then check in Settings > Account to make sure you are on the correct account. If not then you can Sign Out from the Settings section and sign in with the correct account.
On Apple TV devices make sure you are using the account associated with your subscription (Apple ID if you signed up on iOS and STV Account if signed up via the web) - and try Signing in and out of the app via the Settings section.
Make sure you are watching Catch-up or Downloaded content.
Ads will still be shown on the Live stream and on a very limited amount of Catch-up content. If you only see ads on one show and not the others then it is likely to be a rights issue with that show, if you see ads on all Catch-up shows then you might want to try the following.
Check that your subscription is still active.
If you signed up in the iOS app
This requires you to be on a device linked to the Apple Account you pay your subscription from.
You can do this by going to Settings and checking what is listed next to the Plan section, this should say Player+
If this shows Player Free - then click on the Plan option and use the Restore Purchase option - to reapply your subscription settings.
Before restoring your purchase please make sure you are on a device linked to the Apple Account you pay your subscription from AND are logged into the STV Player account you originally signed up with.
If you aren't on a device linked to your account then the Restore purchase will fail and if you are not on the correct STV Player account then the restore purchase will only be temporary.
You might be at your device limit - any devices connected over the 3 allowed - will not see Player+ benefits.
You can check this by going to Settings and clicking on Manage Devices - this will show a list of the current devices registered.
If you cannot see the current device listed then you can use the Remove option to free up space, these can always be added back later. Once a space is available and if the current device needs to be added you will see an Add This Device button, clicking this will enable the current device for Player+