Remember, the subscription is to the online service. To export from an application you'd have to be using the desktop application Acrobat. Acrobat is not free and not available for mobile devices..
Once you have logged into the online service with the email address and password you used to subscribe (your "Adobe ID") you should be good to go.
I paid for a sibscription to export files
Is the name of the subscription that you have paid for "Adobe Export PDF"?
You can use the Export PDF service in the mobile version of Acrobat Reader on your iPhone/iPad.
Please note that Adobe Document Cloud paid subscription services (Adobe Export PDF, Adobe PDF Pack, Adobe Acrobat Pro DC) are available via the mobile version of Acrobat Reader as well as the desktop version and a web browser (https://cloud.acrobat.com).
- Launch Acrobat Reader for iOS on your iPhone/iPad.
- Go to My Account. (See the screenshot below.)
- Sign in with the Adobe ID that you have used to purchase the Adobe Export PDF subscription.
In the Adobe Export PDF section, do you see (a) "Subscribed" in light gray or (b) "Subscribe" in green?
The Adobe Export PDF subscription entitles you to convert from PDF to other supported file formats (e.g. Word, Excel, PowerPoint, RTF).
If you would like to convert from other supported file formats to PDF, you need the Adobe PDF Pack or Adobe Acrobat Pro DC subscription (which supports conversion from/to PDF).
I go into the application it disallows me to perform such task.
Would you tell us which task you tried to perform? Which item in the user interface did you tap?