delete from your database > options table > all option-name starting with ai1wm (like ai1wmge_plugin_key)the same problem here
next open constants.php
and remove the the line
define( 'AI1WMGE_PURCHASE_ID', '00000000-0000-0000-0000-0000000' );
the last part between ''
you will end up with this
define( 'AI1WMGE_PURCHASE_ID', '' );
save and refresh