Garage Sale 7 free pictures service purchase option for GTC listings now not available anymore?

As per title:
I am using Garage Sale 7.0.21b1 (857)
I have purchased a one month paid subscription last month to Garage Sale 7 free pictures service and now wanted to buy it again but this time going for the yearly subscription at 29.99. However when going into Garage Sale preferences > GTC image option > purchase all I get is: Could not process your shopping cart. Please try again later.

please advice

thank you

Sorry, that error message is a bit misleading. Purchases from within GarageSale 7 can no longer be made.
If you have macOS 10.12 installed you might want to check the new GarageSale 8 (the GTC image option is included in GarageSale Pro):
https://www.iwascoding.com/GarageSale/index.html

If you decide to stay with GarageSale 7 you can switch to eBay’s picture service in the GarageSale preferences > eBay > eBay Images.

Regards, Kristian