Tasker is sometimes disabled until I log in to Google Play

What I did

I paid for Tasker and signed out of Google Play. I have most app permissions turned off. I use a Google Pixel with LineageOS 16, an Android 9 variant.

What I expected

I thought that I could use Tasker while signed out of my Google account.

What actually happens

Every few days I get a notification: 'Trial period ended. Sorry, you can't use Tasker until you purchase it from the Google Play Store.'

If I open Tasker, the Play Store quickly opens instead.

When I log in, the notification vanishes and I can use Tasker again.

I then log out of my Google account, but I get the same problem days later.