If you're trying to install products included in the subscription plan, please check mExtension
If you're trying to install a product purchased a one-time payment order, make sure that mInstaller is up-to-date - you can do that in mInstaller settings. Once it's updated, check if you can see your purchases.
I've purchased a product, but it's not showing up in mInstaller
Purchased product can't be found in mInstaller