Hi @Gav_Riggs
The count doesn’t go by the number of invoices/purchases entered, but rather by the number of ledger entries. All L and XL accounts are required to have a Power User Subscription (which is the £54/£45 + VAT) as of 1st December.
There’s a quick guide here to explain how sizes are calculated etc.:
http://community.quickfile.co.uk/t/account-size-explained/8781
I hope that helps, but if you do need further help, please let me know 