License activation issue — key resets after page reload

Hello!
I have a problem with WooCommerce Product Variations Swatches Premium license activation.

After I insert my Auto Update Key, the plugin shows
“Your authentication is successfully”,
but after refreshing the admin page the key disappears, and the plugin again shows the “Activate” banner.

So the key is not saved into the database.

What I have already checked:
• I deleted all old plugin data from wp_options (including any old/invalid swatches options or transients)
• I re-installed the plugin using the fresh ZIP file from my Villatheme account (not Envato ZIP)
• No cache plugin or security plugin is blocking requests
• Hosting does not block outgoing HTTPS connections
• The option vi_woo_product_variation_swatches_params still has “purchased_code”;s:0:””; after activation
• Everything else works, but the plugin does not save the key

Please check:
• Is my Auto Update Key valid?
• Is there any activation limit exceeded or blocked domains?
• Can you manually reset/activate the domain for my license?

Thank you!